Android crashing, likely lost encryption keys/phantom encrypted content

Thanks Again Ajay. Just to say that I've already been doing as close as I realistically can to your advice.

This post suggests I may have to go nuclear: Joplin trying to sync file from note, but file has been removed - #7 by JackGruber - Could anybody advise if it's possible to have Joplin for Windows installed and logged into one ("source") account, and also Joplin portable open and running on the same machine at the same time, and logged into a different ("destination") account? This as a way to essentially abandon my existing account and hopefully leave these issues behind.

Or as per your previous advice to another user here Bug report: Attachments not syncing - #9 by ajay, how would I replicate the step of deleting the profile on Joplin Cloud, to continue using my existing account?