Filename Requirements for OneDrive for Business Files
Files that you are syncing from your computer to OneDrive for Business should not contain any of the following characters in their name:
\ / : * ? " < > | # %
Also file names should not start with a period.
The use of any of these characters in the name of the file (or starting a filename with a period) will generate a syncing error and the file will not upload to your OneDrive for Business directory.
The following error will display above your taskbar:
If you click to view the error, you will see a message indicating there are invalid characters:
If you rename the file, removing the invalid characters ( \ / : * ? " < > | # % or a period at the start of the name,) the file will now sync properly.