toeto I'm sorry to hear you're having trouble. I understand the problem you are experiencing, but unfortunately it is difficult to determine the cause from that GIF alone, so could you please email us the Spine project that can reproduce the problem?: contact@esotericsoftware.com
You only need to send us the minimum amount of files necessary to reproduce the problem. For example, if you can reproduce the problem without images, you do not need to send the image files. (Just send the Spine project).

toeto Thank you for providing a Spine project that can reproduce the problem! I have found this to be an easily reproducible bug, and have created an issue ticket for this: EsotericSoftware/spine-editor776

The details of the conditions under which this problem occurs are described there. However, since the problem occurs in such a common use case, it would be difficult to work around.

We are sorry for the inconvenience, but I hope you can wait until we have completed the fix.