This is the second time that this has happened. When I hit undo, majority of the craft will go lurid purple, and any further action, including saving and reloading, and pressing play, will then Delete any part that is purple. I haven't found a way to fix this, it just happens.
http://m.imgur.com/rHjUos3,FWZA31y
@qwert13357 but the thing is, it deletes all the texture-less parts, and they don't come back through part redo
Hmm. Seems to be an issue with the graphics I assume? On my Phone Medium Graphics on any game will show it flickering and the terrain would be in squares stitched together