I ran into the same bug trying to create a superflat world with only air in snapshot 15w34d.
Presets I tried:
3;minecraft:air;1
3;0;1
Both create an air-only world, but you are unable to move outside of teleporting.
While in this immobile world, I used /setblock ~ ~ ~ minecraft:stone to create a block at my legs. It created the block but didn't push me out of it like in 1.8. I stayed standing within the block, unable to move.
Using the Z-axis mirror (< >), you get the same results for paintings and items frames that you get without mirrors. Painting misplaced at 0 rotation and 270 rotation. Item Frames misplaced at 90 and 270 rotations.
Using the X-axis mirror (^ v), the paintings are all correctly placed at every rotation. However, the Item Frames are misplaced at the 90 and 270 rotations again.
Aniline Selenic
MC-57701![[Mojang] Grum (Erik Broes)](../../../data/assets/gravatar/grum.png){kind=small}
Normal
2016-05-19_14.18.18.png
I ran into the same bug trying to create a superflat world with only air in snapshot 15w34d.
Presets I tried:
3;minecraft:air;1
3;0;1
Both create an air-only world, but you are unable to move outside of teleporting.
While in this immobile world, I used /setblock ~ ~ ~ minecraft:stone to create a block at my legs. It created the block but didn't push me out of it like in 1.8. I stayed standing within the block, unable to move.
If this is Working as Intended, I'll gladly post this as a suggestion instead. Thanks!
Possibly related to this, Item Frames have a similar issue.
When the structure is rotated when loading, the item frame (with item in it) will be floating in front of the wall.
This happens at the 90 and 270 degree rotations.
I added additional screenshots showing the floating item frames.
Testing with Mirrors:
Using the Z-axis mirror (< >), you get the same results for paintings and items frames that you get without mirrors. Painting misplaced at 0 rotation and 270 rotation. Item Frames misplaced at 90 and 270 rotations.
Using the X-axis mirror (^ v), the paintings are all correctly placed at every rotation. However, the Item Frames are misplaced at the 90 and 270 rotations again.
How large is your structure? Structure blocks are limited to 32x32x32.