MMPK Labels with Python Expression not displaying

[AndrewBowne]

I have a couple feature classes in an MMPK that use very simple Python expressions to label features.  For some reason these labels aren't being rendered.

Are there limitations to labeling features with any sort of label expressions?

MMPK created using ArcGIS Pro 2.9.1

[MarkBockenhauer · Accepted solution]

Use an Arcade expression instead.   Arcade expressions are supported throughout the ArcGIS System (ArcGIS Pro, ArcGIS Runtime, ArcGIS online).  Python is not supported for all.

[AndrewBowne]

That worked, Thanks.  

Any thoughts on adding some sort of notification when packaging the MMPK?  I believe there is one when it's a VBScript expression.  Maybe it would be worth while to add one for Python?  This would have been helpful to know before creating 129 MMPKs!