I was doing a project. Everything was great I setup models, scenes, animation was almost done. I did car physics: wheels, carcass with constraint. Simple stuff. Thing is I did animate this car and rigid body properties did not disappear till at some point I opened blend file and there was none(rigid bodies, rigid bodies constraint objects). After two days I still don't understand how and why they disappeared. What could possibly cause it? I can't recall my exact moves but I did nothing fancy just simple animation and scene setup. Blender version 2.80.53.