The sorting in one of my tables disappeared twice today.
The first time I thought I did something wrong. So I added it back and made sure I clicked the check mark to save.
Now the second time, I’m pretty sure it disappeared by itself.
Sort and filter setting aren’t saved automatically, but if you save them (click the green checkbox that shows up on top, or see Search, sort & filter - Grist Help Center) they should get preserved.
If you saved, and then the sort settings got cleared unexpectedly, then it looks like a bug. I tried to reproduce with “Use choice position” and adding choices, but couldn’t reproduce. It doesn’t sound like a likely culprit, but I can’t think of what it might be.