I was stumped by an error when calculating over global ID's from my records to a parcel layer (a lot easier than manually doing it for a half a million parcels).
It seemed that there was a bug because it would get to 5%, freeze up and error out. The error message was extremely general. Just a 999999 error. After a week of trying to work around it I realized it was actually because you can't edit a feature from the fabric out of an edit session.
It would save a lot of ArcGIS Pro fabric users heart ache if that edit session error were more clearly stated or there was a way to detect that before trying to run the process.