Hm I see… well I am now compiling the ui files with the python module pysideuic which has a compileUi() method in place. Changed up the build_resource.sh to run a small python script that invokes this command when compiling the ui files. This works fine for me at the moment.
Still I think it’s strange that the PySide installation for windows comes with a compiled pyside-rcc binary but lacks the uic equivalent. ¯_(ツ)_/¯