Unfortunately, this recipe (I saw it in other questions) doesn't work in my case.
I created new empty profile
Configured sync to Joplin Cloud and encryption password
Started sync
Joplin showed message to login into Joplin Cloud again
I entered the credentials again (and tried the button that checks them)
Joplin tried to sync and showed the login message again
Repeats the same
My Joplin Cloud was corrupted and overwhelmed when I tied to sync Joplin in my spare notebook which I've not been using for several months (it duplicated notes and attachments).
I don't know how I can clean my Joplin Cloud.
Now I'm in process of uploading my data to Dropbox. It works slower than Joplin Cloud, but it works. If I can, I'd prefer to stay with Joplin Cloud.
I expected to have a data clean feature in Joplin Cloud web interface as any other cloud services usually have, but nothing is provided.
No unfortunately we only support the above method. But in your above description I don't see what the issue is. Just sync, delete and sync again? Or if you have a specific error message that shows up please share it here