Rigid Body Object gets shot in the air although "no changes" were made

Hi there,

for some reason one of my rigid body objects (the lamp) gets shot in the air at frame 1 what I cannot understand as I did not make any changes to the corresponding settings.

It is an active rigid body with no keyframes and no animation. The object has no modifiers and no constraints. Origin is centered.

It should just sit on the floor until it gets knocked away by some other objects later on. That worked for quite a while but now, ir does not.

I deleted all bakes and made a new bake but it did not help. Also, the physics cache starts at frame 1 and goes until the end of my simulation.
I also opened an earlier version of my project where I had no issues with this object, deleted all bakes and had no issues after that. The object stands still as it should do.

Then, in my current version of my project, I added a cube just for testing rigid body. I placed it in the air quiete next to the lamp and started the animation without bakeing. Cube and lamp are flying away.

I have to place the cube far away from the lamp, so the cube does not get shot away. The cube falls as it should do but if it hits the floor, it is moving in slow motion whereas my overall animation (the “frames”) is running with normal speed.

If I place the lamp somewhere else, it behaves as it should, with correct physics => that is crazy.

Could it be that it is no problem of the lamp but of something what is around the lamp? Again, no clue what I did change there.

Well, that bugged me a lot and I started deleting more and more objects near to my lamp and tested if there is a different behavior in physics.
I came to the conclusion that I had a non-rendering cylinder (in viewport only visible as “bounds”) parented around another object which functions as a “rigid body shield” (I dont want objects getting inside the “real” cylinder which has open parts.

So, that “badboy shield” had a collison detection shape of “cylinder”. Pretty obvious you might think, right?

As I did not check if that affects other objects, especally the lamp, I went on with my project and left it as it was as this cylinder only appears for a very short time in my animation and I never would have thought that it would cause problems with this settings.

So, changing the collison shape to “mesh” is the solution.