The office where I work has a Dropbox business account with 2TB of storage available. That account is under the office manager's name. Folders in her account are shared to my personal account.
About a week ago, our largest (2.26. GB) records folder got moved to be a subfolder of another folder. I thought for a minute it had been deleted, but I found it and moved it back where it was as a top level folder. It now shows up online in Dropbox, and is still shared with my account, but it does not appear in my File Explorer list. The folders from my own Dropbox account and other folders shared with the office manager's account are there, but the big folder (and the one I use most often) is missing. A search for it in File Explorer comes up dry.
The only other clue I have that something might be sideways is that the Dropbox icon in my task tray has a red something showing over it. I'd be more detailed, but it's too small for me to make out. Here is a screencap:

In a pinch, I can always access files in the online folder via the web interface (logging onto Dropbox with the office manager's account), but I would much prefer to access files via File Explorer, as I have done for the past ten years or so.
I searched other posts on this forum before starting a new discussion.
I have tried rebooting the computer, re-installing the Dropbox app, sharing it again from the office manager's account, and ensuring that Dropbox is synced with the online files. I'm running Windows 11 Home and version 186.4.6207 of Dropbox.