I'm glad you found the source of your problem. It will certainly be useful to others.
Personally I hate any form of Cloud, including Dropbox. On the net I only go there with the Smartphone, while serious things I do exclusively on the Desktop NEVER connected to the network and only updated in manual. For decades we have been feeding, with everything that concerns us, servers whose "parallel uses" we don't know at all. Now we find out that Artificial (?)Intelligences(?) are fed (or do they "feed"?) with everything that is available and poorly protected on the web. Basically we have put ourselves, for our comfort and with our superficiality, the premises for some "superior entity" to sooner or later do and undo what it will prefer. I strongly doubt that there will be a human at the head ... and maybe "a good one" ...