Onedrive: Excel sheet won't open correctly

I have been using an excel spreadsheet for 4 months now and have always saved it on Onedrive.

Now when I log in to Onedrive the spreadsheet is correct but when I open in Excel it is out of date by about a week. The error message at the top of the screen says 'UPLOAD FAILED We're sorry, someone updated the server copy and it's not possible to upload your changes now'

Any ideas? I really need to work on this today.