Hi ArcGIS Hub team.
ArcGIS Hub seems to be missing some fields during its indexing/cataloging.
The following item was published from ArcGIS Pro (data source was FGDB), with 15 records. As you can see, ArcGIS Hub shows only 5 fields, although if you navigate to the REST endpoint you will see it actually has 8 fields (plus object id)
https://adamtest5-govportal.hub.arcgis.com/datasets/govportal::adamdatatest1/about
But if I first truncate the dataset and publish without any data, then once ArcGIS Hub had indexed the data I add the same 15 records using the Append Tool in ArcGIS Pro, then all fields appear correctly, at least initially. Subsequently I updated the item and the fields disappeared again.
In the real ArcGIS Hub site there are many datasets which have this issue - missing fields. Are you able to see why ArcGIS Hub is not showing the first dataset correctly?