ive found the built in ways to be very inconsistant... currently anytime i need to add a external python library i do a normal pip3 install and go find where it installed it which normally for me is in "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages".   i then copy and paste the installed libraries into a "Python Externals" folder in the user folder and its worked every time so far. i think i have 5-6 libraries in there.