My code looks the same as yours and works.
The only difference is where your code reads
aprx = arcpy.mp.ArcGISProject('Current')
mine reads
aprx = arcpy.mp.ArcGISProject(r'C:\Users\NAME\Documents\ArcGIS\Projects\MyProjectTest\MyProjectTest.aprx')
I opened a project , saved it, and added the script to run from the toolbox.
If you go to Project Tab > Info there is an easy copy path button for pasting your project name
Also, before hand I went to the Project Tab > Package manager and cloned my environment and updated all my packages
I am running on Pro 3.1.3
Python-2.0