Hi, @Blair M
You'll need to delete some files or buy more storage, here's how: https://support.microsoft.com/office/my-onedrive-says-it-s-full-f0a8a922-d971-497e-b0c6-7b9a47c617c0
After freeing space (or purchasing additional storage), it can take up to 24 to 48 hours for everything to fully update across your account. I’d recommend waiting that time and check again OneDrive after that.
If the update is still pending after 24 hours, you can try unlinking and relinking your OneDrive account, or resetting it. "Unlink and re-link OneDrive" https://support.microsoft.com/office/unlink-and-re-link-onedrive-3c4680bf-cc36-4204-9ca5-e7b24cdd23ea
Should you need further information in the meantime, please feel free to let me know.
Thanks!