ab12345678abcd Thank you for submitting your Spine project file! Based on my testing, this appears to be a bug that existed up to version 3.8 and was resolved in version 4.0. Although many mesh-related improvements were introduced in 4.0 and the exact cause is unclear, it was most likely addressed by the following fix in 4.0.41-beta:
Fixed texture packing whitespace stripping for meshes.
https://esotericsoftware.com/spine-changelog/archive#v4-0-41-beta
Fortunately, repacking the textures in a newer version seems to resolve the issue. While skeleton data must be exported from an editor version that matches the runtime, texture packing can be performed in a newer version without any problems. Using Spine 4.2 or a similar version solely for texture packing should therefore be sufficient.
If you would prefer to run only the texture packing step in the newer version, it is easier to use the command line interface (CLI) than the graphical user interface (GUI). Please refer to the user guide for details on using the CLI.
We would appreciate it if you could let us know whether this resolves the issue.
