I can't save an Adobe PDF file with Windows File Explorer open

I can't save an edited PDF with the Windows file explorer open. I thought it was because another user had the file open, but then I discovered that I can save the file if I close the file explorer first, which doesn't make sense. I get an Adobe Acrobat message stating, "The document could not be saved. The file may be read-only, or another user may have it open. Please save the document with a different name or in a different folder." I removed all other devices from the Dropbox account and that did the trick for a little while, but now I'm getting this message again any time I edit a PDF and try to save it where it is. I close the window, hit save, and locate the file again. How can I fix this so I don't have to close the file explorer every time I edit a document in Dropbox on desktop?