"Can't Find" Excel Sheet

Good morning. Curious if anyone knows how to rectify an error (clicking to open an Excel sheet): "Sorry, we can't find --(file with location info ahead of it) -- Is it possible it was moved, renamed or deleted?"

I do use Dropbox from finder but I've had this issue before and am not clear if it is / is not a MAC settings related issue. I do see that I have read & write permissions for the folder, and this is tarting to become super frustrating. I CAN open the file if I drag it to my desktop, but not being a super tech person, I don't understand why.

I do see "Library/CloudStorage/" included in the error message (Dropbox only comes after second slash).

Would be grateful if anyone had any ideas! Thanks so much!