NeoAlexLee Thank you for sending me the repro project! I have confirmed that I am able to reproduce the result you described, but this skeleton seems to have a special setup.
From the project you sent, I see that your skeleton is set up by cutting out a portion of the image that is already packed, as shown in the following image. Am I correct?:
As far as I have tried with your Spine project, when I did the Polygons packing with all the mesh attachments removed except the hand removed, the output texture correctly contained the hand image. In other words, I suspect that as a result of cropping the image along the mesh hull for another mesh attachment (perhaps the difference image of the hand, since when I delete it, the hand image is shown in the packed texture atlas page), the area of the hand has been cropped and is not shown in the output results.
However, I don't think
Polygons packing is intended to be used in such cases in the first place, so this is not so much a bug as it is a different usage than expected.
Basically, Spine expects you to import images that are separated by parts when animating in the editor, and then combine (pack) them into a single texture atlas page when exporting.
I am not sure how many skeletons you have created in this way, but if this is the only skeleton that is not working for you, and it is working for many others, I think you can solve this problem by separating the hand image only from the current image. If this is the first skeleton you have created, you may want to replace the images for the entire skeleton with separate images to avoid encountering similar problems in the future.