I am having the same problem with not being able to create a list/domain. In this instance, the field was added to the feature layer from within ArcGIS Pro. I had to do that to workaround the problem mentioned in the next paragraph.
I was also having a problem with an added field not calculating values. The field was added after I deleted a field. I kept receiving an error about a calculation not being able to be performed on the XXXX field (where the xxxx field was the field I had deleted and not the one I was calculating).
It seems like I have been having a much harder time with this feature layer than with previous ones I have worked with and just in the past 2 days.
Carmen