Hello! We're really sorry for your inconvenience, and thank you very much for the report! We'll check it out to find the possible cause and try to give solutions ASAP. Just for confirmation: based on your description above we understand that the app works fine for the first time, but has troubles after closing it and opening again at a later time, correct?
1. Deleted the folder you said.
2. Launching Mannequin via Itch.
3. I create a new file, everything works, the window is loaded.
4. Restart Mannequin.
5. I create a new file, everything works again, the window is loaded.
6. Save the character's test file.
7. Restart Mannequin.
8. I select a character file, and try to change the pose, clothes, etc. and again I get to the endless loading of the window.
It seems to me that this is a problem in the save files, when reading the file, an error may occur somewhere in the program code, check it.
I can give you a save file if you need it.
That would be very helpful! You can send your save file for further analysis by us via hello@ar14.works
Again, thank you very much for your cooperation!