GIMP auto-rearranging layers(!?!)

Hey all, on more than one occasion I’ve saved a reasonably complex xcf with a significant number of layers nicely arranged in hierarchical groups (like for which the functionality provides).

I’ll reopen the xcf later (normally the next day) and the layer hierarchy has been flattened (so layers are on the same level as the groups they were previously in, they’re now all on one level and the order of the layers/ groups has been randomised). Which means the image is just a mess and I have to work out what went where (if I can) and spend significant time remediating.

The only “theme” that might be causing this (and that I suspect but can’t confirm) is that sometimes I’ll save an xcf with an unanchored transformation/ pasted layer - but still, there’s no “don’t save this” warning I can see :slight_smile:

Is this a known issue, maybe with a known solution?

Happy to hear it’s a user error (because of something of which I’m currently ignorant)