InDesign and Dropbox - Please Help

I have been using InDesign and Dropbox for all my files for one client for years. After they hired me and gave me an office, I would access those files from my new office, as well as home office. A problem arose because I didn't want to share all of my other files with work, so I opened a business Dropbox there with my work email, and shared just those files with myself. That has been working well for several years. After a couple years, I removed my InDesign, and had the company subscribe for me there, so I could have free access on my own tablet without switching machines. It still worked well.

The last week, things were a little wonky, but I also had a modem go out. I had to sign back in to Dropbox after replacing it, but the accounts all stayed the same. They worked fine for a few days. Suddenly, today, I am in an InDesign document -that I was working in with no problem last night- and when I go to place an image, it says that it's not available. When I look at files in Dropbox they look fine, but when I look at them by trying to place an image, every image in dropbox has a big grey X on the lower left hand corner of the naked* thumb, and it says "the file cannot be accessed by the system." (*by "naked" I mean, no thumb image, only generic image that represents what kind of file it is along with the title). Ah, and 1 more item of note: All images that were placed in this document last night and before (from the same Dropbox), are linked perfectly, with no problem.

Is this a problem with Dropbox and the newest upgrade, Adobe, or something else like new path rules or something? I have a deadline. I'm under "stay at home" orders, and I can't seem to find the answer. Thank you to anyone that can help me troubleshoot this problem!

Dena "ArtistJoyful"