The OneDrive folder is excluded from the backup by default because the data there is already backed up on one hand and, on the other hand, is sometimes only stored in the cloud and not locally on the hard drive. Therefore, it can happen that scheduled backups do not capture files in the OneDrive directory and thus do not back them up.
Two measures are necessary to ensure that files from a OneDrive folder can also be backed up.
To permanently store all OneDrive data locally, please right-click the OneDrive folder in File Explorer and select "Always keep on this device." This will download all files and occupy local storage space but will remain synchronized with the cloud.
Then create a backup plan in Backup Pro that backs up the desired files and folders. During creation, please remove the exclusion for the OneDrive folder in the "Exclusions" tab.
If you have already created a backup plan, you can adjust it under Backup Plans > Backup Plan > Settings > Source File Settings. In older versions (up to Backup Pro 26), you will find the option under Backup Plans > Backup Plan > Actions > Change Plan.
This way, Backup Pro will be able to back up your OneDrive files as well.