Well hopefully anyone else who has these issues wont have too much trouble finding this thread, as the solution seems fairly simply in the end!
When you say you could use NCM without usb-modeswitch, would one of the other modules have installed the /etc/usb-mode.json file or are you saying it isn't required at all?
Also - do I have to reguster to vote on those bugfixes? I cant see a way to do so.