itch.io

I've had that happen a few times myself, and it's been difficult to figure out what's causing it. My only solution has been to delete those files manually because they get corrupted somehow. Once you do that the slots become available again. Though it's not ideal, because it should just work.

I'm uploading a new version later today, so hopefully, that version works better for you! *fingers crossed*

And sorry for the late reply. -.-"