Hello there.
This is a problem that’s been recently reported/noticed, there’s no space left for that partition.
Go and read these threads → Version 22251 Issues Arising? & Some APIM Settings Going Back to Default.
It’s yet to be determined if this issue affects 22251 or other builds as well.
But basically, ideally, you need to reformat the unit if possible.
Review the quoted thread, if you have any feedback or questions about it, post them there.