I am not sure this is an issue, but does the Gotthard bahn work correctly with the Steam Workshop, I just find it strange that there are no scenarios for it, nor is it a dependency for other workshop items, something to look into ?
I'm not sure why no scenarios exist for it but there are a lot on RailSim.de https://rail-sim.de/forum/filebase/filebase/1319-gotthardbahn-alpine-classic-erstfeld-bellinzona/ You will need some other Swiss Freeware & Payware to run most scenarios
