I've got this issue with one specific file only.
When I open this file, some images are not found. Meanwhile they're present in the folder the image path is refering to. The images won't be loaded in Spine until I open the photoshop file in which I make the images (we use an image generator which creates pngs of the layers).
It's fixed for one turn only, because when I re-open the file I've got this very same issue (even though I save etc). I don't have this issue with any of my other Spine files.
What is this?