I am seeing that the Attribute Table and the Attributes pane show GlobalID differently. One is all upper case and one is lower.
I would call it a bug.
thanks
I just posted in the other thread about this @DougBrowning then found this one. Very frustrating that it's still an issue 6 years on!
I'm running into this issue in ArcGIS Pro 3.5.0.
I have a point dataset with related table using GlobalID to a GUID field, set it up and Pro, worked okay, uploaded it to AGOL and now when I view in Pro I can't see the related records - if I select a record and click on Related Data, it shows the relate exists but there is no number next to it indicating how many records are related. I can however see the related records using the pop-up window.
The only potential cause I can see is this uppercase/lowercase issue.