If you're seeing this error:
Please check your file name(s) for the following invalid characters. You'll have to use characters supported by Microsoft.
One other possibility is that there is an "extra" space after one of your file names. You might see something like this:
This will cause a problem with the folder associated with this recording. If you have trouble renaming this recording, please contact firstname.lastname@example.org and we'll do our best to help.