4.7.6 (ie the latest) and I just tried a blank project and it worked OK. So it’s just this one project. For reference I had some landscapes I created in 4.6 but they were having really bad collision problems (after sculpting the landscape the collisions were in the wrong place) so I deleted them (before I upgraded to 4.7). Is there a way to purge old/bad landscape data or something if that is the problem?