This issue is very recent, and happened a couple of days ago when I noticed that I was not able to build certain formulas in my Excel files shared in Dropbox. When I start to build a formula (usually with the "=" sign), and then try to pull a number or data from another sheet within the same file, the cell where I want the result will be empty, and the result of the formula will appear on the sheet where I wanted to pull my data from.
Not sure if I have been clear with my issue, but bottom line is that I am not able to work formulas on Excel files shared on my Dropbox. I tried by moving the same file from Dropbox to my hard drive, and there it worked without any issues. Same thing happens when I open a new Excel file (without saving it).
My Dropbox version is 23.3.15 and shows up to date.