Hello, physics are intended mostly for runtime use and currently cannot loop seamlessly, however, where there's a will there's a way!
if you need to export a video or gif and have them loop here is a way to get physics to loop seamlessly:
- copy your animation frames
- paste them maybe 2 or 3 times on the timeline, one after the other
- on export match the frame rate with your project so range works the same
- check range and set the range so only the last loop is exported (eg if your animation is long 10 frames, paste it so it lasts till 30, set the range to go from 21 to 30)