Overwriting a feature class produces an error while loading a layout with a map series in Python 3 for an ArcGIS Pro project despite setting arcpy.env.overwriteOutput = True.

Workaround

Set the project without a map series.

1. Create another ArcGIS Pro project. One with the same two feature classes in the Map and no Map Series.
2. Modify the arcpy.mp.ArcGISProject variable to point to the new ArcGIS Pro project.
3. Run the script.
4. The overwrite will work.

Steps to Reproduce