Hello,
It could be that since the file is in the OneDrive folder, it is not recognizing the tags data in the files. Another possibility is that you don't have it displayed. Try the following:
1- Enable the "Tags" column in file explorer: If you change the View to "Details", you can then right-click on the columns to select which categories appear. If the file has Tags data, it should show there.
2- Open the details pane: Similarly, in the View menu you can open "Show" and select the Details Pane, which should show the Tags information.
The metadata should still be there even if File Explorer is not reading it.