Is this a Pro Bug or a Server Bug

[ThomasColson]

When publishing a SDE 10.7 feature class to server 10.6.1 from ArcMap 10.7.1, when I set the Display Expression, the Display Field is correctly reflected:

In Pro, when I PUBLISH, same behavior, but when I OVERWRITE, whatever I set in the Display expression (attribute value, expression, string) is not honored, and only the original display expression when first published remain. 

It seems you can't alter the "Display Field" of a feature service using Pro? 

[RobertBorchert]

Don't overwrite it the first time. create the feature service direct from Pro I would say it is Pro and ArcMap speaking the same language but  with different accents.

[ThomasColson]

Unfortunately not in the cards, we have several hundred feature services originally published from ArcMap, and as things come up and make changes, publish those changes from Pro. In addition, even if it's published from Pro the first time (new service), it is not possible to alter the Display Field in the REST using Pro by overwriting.