If you created the file on the iPad, you have to be syncing the file for it to be present on other devices. Were you syncing with one location and recently added another location, which all devices are now syncing with?
No. All devices are showing themselves as fully synced - but no device can download the file (including the device from which I originally created it). I created the item by sharing a PDF from GoodNotes via the Share Extension (Clip to DEVONthink).
I’m thinking I’ll look to see if I have the original then delete those entries in DEVONthink Pro Office.
Seems like a strange bug though. Like the file is there but inaccessible.