Under the label placement properties, you will need to add a very high feature weight to your orange polygon (a weight of a 1000). For more information see Prevent labels from overlapping certain features—ArcGIS Pro | Documentation.
I have used this approach successfully in the past for feature classes. Only other suggestions would be to check you are using the Maplex labeling engine? Then what data type is your orange layer? Not that I would know that much about what layers work and which may not (I suspect map services may not).
Probably best to log this with tech support.