Hi, wow strange, I already fixed a similar bug it was because the asset resync to their path when focus in and when asset was changed it didn't sync to the right path but seems it's another issue. I will investigate and fix for next update.
Nice graphic style by the way. Also I link a little tutorial about bones animation : https://pixelover.io/docs/tutorials/bones_animation/ and if your different images have same origin you can create animated image from them (by just opening for example all the arms variants in same time) but don't hesitate to ask if you think about an improvement which could help you.
Edit: ok I understood, it's when multi select and focus in. Sorry about that, I will fix and send you pre-release with the fix.
To prevent this, you can disable this auto sync in main settings : 