CIMSpatialMapSeries' margin values not being applied?

[ODWC_GIS]

I'm almost done with a script that'll export shortened links to each feature in an Experience Builder App, but I'm stuck at an unusual point.

My methodology involves ArcGIS Pro and the programmatic creation of a Spatial Map Series, and the derivative URL Parameters for an ExB hyperlink therefrom.

It appears that the only way to create a Spatial Map Series from ArcPy is to call the "CIM Spatial Map Series Object and populate its properties."  I appear to be having issues with the Map Extent parameters, specifically, setting them to anything other than Percentage.

• extentOptions
• marginType
• marginUnits
• margin

 The Usual GUI Spatial Map Series' Tool clearly reflects the CIM Options for marginType (Percent, MapUnits, or PageUnits).  But any attempt on my part to specify anything other than Percent in the CIM just gets ignored.

    Attempting This (4-mile margin according to the MapUnits):

 Results in this:

A 4 Percent Margin.

This has got to be User Error.  Anyone reading this have any ideas?

[ODWC_GIS · Accepted solution]

I found it.  Wish I could delete the question now.  It was my specified wkid of the projection, which was not correct at all.  Me intending to use "Miles" requires the use of: 

'uwkid': 9093 

 apparently.  I feel like this one came out of left field, and I don't know where exactly it comes from: LinearUnitId (arcgis.com)