I am encountering issues with ArcGIS Pro (2.8.1) not sorting numeric attributes correctly as shown below when Urgency_CR is sorted ascending (see snapshots 1 and 2 below). When I use the custom sort, and select ascending it sorts correctly. On further investigation, it appears that Pro is sorting on the attribute to the right of the attribute I am trying to sort on. For example in the 3rd snapshot below, I tried to sort on RoadwayElevation Ascending using the drop down and it did not work. When I opened the Custom Sort window it showed the attribute to the right being sorted (I had not previously sorted on that attribute).
I have also had an issue where I was not able to sort an attribute (ascending and descending were shaded out in the dropdown menu), but I was able to sort using custom sort.
What field type are those fields you are sorting?
Urgency_CR is numeric (long) as shown in the snapshot.
RoadwayElevation is numeric (double).
Are they shape files or feature classes? If they are feature classes where are they being stored? Database or file geodatabase?
Feature classes stored in a file geodatabase. I am using ArcGIS Pro 2.8.1.
Try adding an attribute index or global ID.