gr:
Glad things worked out. But somewhere in this exchange it came to light that you had for the first time recently shared Dropbox access to at least one Scriv project (if not your whole Dropbox Scriv folder) with someone else. Off hand, that would be your odds-on candidate explanation for the mysterious moving of your files (and the packaging of them into a dangerously named folder).
It behooves you to see if the other party unwittingly messed things up, since you would either need to teach them better or rescind access to avoid similar troubles in the future.*
Best,
Personally, I would never give someone else access to the master copy of my important work. I would compile it or make a copy and put in a folder with separate access.
I gave rstricted access to one work file. The link would not have given them any means to delete. Oddest of all, all projects were moved from the proper synch folder to one mystery file called scrivener.scriv.
All is resolved with the quick help of Amber.