Then something here is very very broken and needs fixing. Anyway - I changed to creative and not back. Creative and back does indeed seem to mess things up with the flight model - no doubt because of some nasty untested hacks. Also destroying structures (destroy command) causes exceptions in the console - something else that has been in-yr-face for ages and never dealt with. Just yesterday they had to hotfix a blatant crash because what? it compiles so ship it? Why the hell it needs to mess with flight models and break a load of stuff I do not know - all we need to is be be able to shift-remove remove blocks, bulk add and enable copy/paste etc. TBH bulk colouring could have been s survival mode thing. Actually I would prefer it if creative didnt mess with as much as it did.