This is currently happening to me also. The leads in my instance are not invisible but can be found lying on the ground around the posts after traveling away from the chunk in question and then returning to it. Oddly, it does not happen in ALL instances, only sometimes.
Roobix
MC-13543
That explanation makes sense John, thank you.
I am experiencing this as well. Hitting zombie pigmen while in the nether causes regular zombies to spawn.
This is currently happening to me also. The leads in my instance are not invisible but can be found lying on the ground around the posts after traveling away from the chunk in question and then returning to it. Oddly, it does not happen in ALL instances, only sometimes.