When we add field in ArcGIS online it does not reflect in ArcPro until you close and reopen the project or remove layer and readd to the map at which point you have to redo symbology as arcgis online symbology uses picture instead of custom symbols we originally create.
It would be nice to have option to refresh fields in fields view to avoid all the extra steps.
We tried resourcing layer to arcgis online and that still does not show the field we add until project is closed-reopened or layer removed and re-added.