Attached is a place file including a simple physics contraption using AlignPosition, AlignOrientation and a PrismaticConstraint. When you run the place file the contraption will freak out and rotate all over the place. If you run the place file a second, third, fourth time etc. the contraption will work as normal by staying afloat in the air without any weird rotations. Somehow, the contraption only breaks on the first run. I have also spotted the same broken behavior when uploading the file and playing it online.
broken_contraption.rbxl (46.9 KB)
Below is a video demonstrating the problem. You can see me pasting the model into the place file and running it. On the first run the contraption freaks out. On any other runs however the contraption remains stable.
Expected behavior
I expect the physics contraption to remain afloat in the air without rotating all over the place.