Sorry, I have no idea why it would work with one Steam game but not the other.
Are you launching the plugin through Steam as well? If not its worth a try at least. Add it as a non-steam game, go to properties and enable steam input in it as well.
thanks for the response c:
I tried your suggestion but the same problem persists. My controller is recognized and working with nyarupad but the moment I launch MM+, nyarupad shows (1) Unknown controller and no longer tracks my inputs. I have no mods enabled on the game that could be interfering, so it is a problem with the base game somehow.
Edit: I fixed the problem!!!
I added nyarupad as a non steam game through steam and enabled steam controller input for it. In my task manager, I to the properties of nyarupad and set it to run as administrator.
In the steam controller settings of MM+ I set it to "use default settings" instead of enable steam input.
I launch nyarupad as administrator, then MM+ and it is working now :3