Hi! I ended up solving it, I am going to write a comment explaining how, on the major ticket that has been linked, that has the same issue as me: MCL-22283.
Hi! I had the same issue and I myself opened a ticket that I consider they should mark it closed, because I ended up solving it, so I am going to explain here how I solved it in my case:
So overall in the moment I purchased mineraft and tried to enter my first Username ever, to star playing for the first time Minecraft Premium (like in your Pictures)... I had bad internet connection. Like literally not only Minecraft but some other minor things like Steam not opening would happen in my PC... etc. It didn't made much sense, I thought it shouldn't affect the Minecraft Username setting in the launcher... but didn't work for some reason setting the damn username like in the picture.
And same as this user's screenshot, when going to the Minecraft.net (There's a section in your microsoft profile, called my games and in my games there's a section under Minecraft:Java Edition that says Profile Name, where you can set your profile name as well) in the website, I would try to enter a Username and wouldn't load or mark it as set.
So what I did was a weird resolvement, but just worked. Basically I tried to set a Username in Minecraft.net but instead from my PC I did it with my phone, and as my phone was connected to my house's internet still wouldn't work. I would reload the Minecraft.net page over and over and the username still wouldn't set.
So I just thought about instead of doing it with my Home Wifi connection. IUsed my mobile data to set my username in minecraft.net. For some reason not doing it with my home internet IP would work. Don't know if it's because of the slow internet connection I had... or whatever. that shouldn't affect but just for some reason the IP of my Home's internet wouldn't work. So I set the username with mobile internet data. that has a different IP from the one you have at home.
And the fact that the IP is the issue this makes sense to me because I heard from other users that had the same issue, they recommend you to ask a friend who has internet to set the account for you (because they have other IP). This sucks and It's crazy because THIS PROBLEM is NOT SUPPOSED TO happen, but it happens, and apparently you can get away with setting your Username if you have another IP. So people recommend to check if you have a VPN turned on (this affects your IP) and ask a friend to set for you the account's Username (because they have other IP). In my case I recommend if you have a mobile phone, (your own) or maybe you can borrow it from some family member, and said mobile phone has Mobile Data. Turn off the wifi and use the mobile data to set your Username in Minecraft.net, ... that worked for me. Again this sucks a lot ... because maybe you don't have a friend to ask him to do it for you, or maybe you just don't have mobile data on your phone because you just don't use internet otuside the house... and you are not supposed to now go get yourself some mobile data just for doing this lol.... but It's an option.
In brief: just what I said: If you have access to a phone with mobile data Turn off the Wifi and use the mobile data to set your Username in Minecraft.net. that worked for me.
[+Additional Info. (if interested)] : What exactly happened when I did it?
-In my phone in Minecraft.Net after setting the username the website reloaded and there was a text like: Current Java Profile Name Set: (My user)
and as I went back to my PC and re-opened the MC Launcher, next to the play button automatically showed the username I set from my phone in Minecraft.net . and I could just press play and the game would start loading without asking me to enter the username.
Eliza_Moonlight
MCL-22435
Hi! I ended up solving it, I am going to write a comment explaining how, on the major ticket that has been linked, that has the same issue as me:
MCL-22283.Hoepfully other users can solved it too.
Hi! I had the same issue and I myself opened a ticket that I consider they should mark it closed, because I ended up solving it, so I am going to explain here how I solved it in my case:
So overall in the moment I purchased mineraft and tried to enter my first Username ever, to star playing for the first time Minecraft Premium (like in your Pictures)... I had bad internet connection. Like literally not only Minecraft but some other minor things like Steam not opening would happen in my PC... etc. It didn't made much sense, I thought it shouldn't affect the Minecraft Username setting in the launcher... but didn't work for some reason setting the damn username like in the picture.
And same as this user's screenshot, when going to the Minecraft.net (There's a section in your microsoft profile, called my games and in my games there's a section under Minecraft:Java Edition that says Profile Name, where you can set your profile name as well) in the website, I would try to enter a Username and wouldn't load or mark it as set.
So what I did was a weird resolvement, but just worked. Basically I tried to set a Username in Minecraft.net but instead from my PC I did it with my phone, and as my phone was connected to my house's internet still wouldn't work. I would reload the Minecraft.net page over and over and the username still wouldn't set.
So I just thought about instead of doing it with my Home Wifi connection. I Used my mobile data to set my username in minecraft.net. For some reason not doing it with my home internet IP would work. Don't know if it's because of the slow internet connection I had... or whatever. that shouldn't affect but just for some reason the IP of my Home's internet wouldn't work. So I set the username with mobile internet data. that has a different IP from the one you have at home.
And the fact that the IP is the issue this makes sense to me because I heard from other users that had the same issue, they recommend you to ask a friend who has internet to set the account for you (because they have other IP). This sucks and It's crazy because THIS PROBLEM is NOT SUPPOSED TO happen, but it happens, and apparently you can get away with setting your Username if you have another IP. So people recommend to check if you have a VPN turned on (this affects your IP) and ask a friend to set for you the account's Username (because they have other IP). In my case I recommend if you have a mobile phone, (your own) or maybe you can borrow it from some family member, and said mobile phone has Mobile Data. Turn off the wifi and use the mobile data to set your Username in Minecraft.net, ... that worked for me. Again this sucks a lot ... because maybe you don't have a friend to ask him to do it for you, or maybe you just don't have mobile data on your phone because you just don't use internet otuside the house... and you are not supposed to now go get yourself some mobile data just for doing this lol.... but It's an option.
In brief: just what I said: If you have access to a phone with mobile data Turn off the Wifi and use the mobile data to set your Username in Minecraft.net. that worked for me.
[+Additional Info. (if interested)] : What exactly happened when I did it?
-In my phone in Minecraft.Net after setting the username the website reloaded and there was a text like: Current Java Profile Name Set: (My user)
and as I went back to my PC and re-opened the MC Launcher, next to the play button automatically showed the username I set from my phone in Minecraft.net . and I could just press play and the game would start loading without asking me to enter the username.