Source folder path to watch folder under Synology Docker Portainer installed not recognised

In the Portainer stack I have: - /volume1/docker/mayanedms/watchin:/watch_folder:rw

The “watchin” file does exist. Mayan for basic function works. In creating the source for the “watch folder” I assume this would be just /watch_folder? That saves fine but doesn’t show up as a source when adding a new document. “Default” works fine. Running the “Test” option produces no errors. Not sure where to look for or how to identify the problem. Bought the book to support the software but wasn’t any closer to a solution but it helped with other questions. Pointing me towards a solution would be greatly appreciated. Tried the Synology forum plus a lot of web searching as well.