I have no issues with the Supergirl series when I use the file names structured like “Supergirl.S01E01.mkv”. It puts it in the TV library and sorts by season without any additional steps by me. I don’t think that having the season and episode before the series name is usable at all.
Your folder structure is correct.
As far as google drive is concerned, there may be some gotcha that they are not passing the correct name but I don’t have google drive so I can’t really address that.
I know you have said you have already tried it but I am sure the series name must proceed the season/episode number as anything after the season/episode is ignored. So it should be named something like:
After making the change, if it doesn’t appear correctly then ry the edit Metadata option again and see if you can select the correct TV show.