I am having a similar problem that is happening in Excel.
I tried uploading the file to OneDrive manually and I got an error saying the file was already open on my system. It was not, but I had about 13-15 other Excel files open at the time. I closed them all and then was able to upload the file manually through
the OneDrive web site successfully.
I noticed that the Upload Failed message drove me to the Microsoft Office Upload Center which was also sitting in my system tray. I also noticed that I have a OneDrive app in my system tray.
With both system tray apps (OneDrive and Microsoft Office Upload Center) running, I got the same error message when I opened and attempted to save the file to my hard drive.
I tried Pausing synchronization for MS Office Upload Center by right clicking on it in the system tray, then choosing Pause for 2 hours.
I tried to open the Excel file again and this time it took a really long time to attempt the save, and while it was attempting to save, OneDrive tray icon had a synch icon on it and was attempting to synch the file. Eventually it failed with the same error.
This time, I re-enabled MS Office Upload Center sync and paused OneDrive sync for 2 hours. Now when I opened the Excel file it quickly auto saved whenever I updated a cell.
I have not tested this extensively, but it seems there is a conflict issue at the moment with OneDrive and MS Office Upload Center apps.