Hi Again,
I still don't know what is causing the problem, but I (with the help of a programming colleague) was able to find a quick fix:
In this file : "C:\Program Files\Allegorithmic\Substance in Maya\2019\plug-ins\substance\maya\core\hypershade.py" simply comment out the variable "$res" causing the issue by "//" like this:
def acquire_hypershade():
""" Gets the hypershade object from Maya, returned as a string """
return maya.mel.eval('global string $gHypershadeNodeEditor;'
'//string $res = $gHypershadeNodeEditor;')
I don't know if it causes any other issues down the line, but for now it works for me
