Missing files when using File templates via "⌃⌥N" shortcut

I'm trying to create a new C# file via the ⌃⌥N shortcut while I'm already in an existing C# file, but after pressing ⌃⌥N, the list that appears contains the entries found under Preferences -> File Templates -> Other languages, and not those found under File Templates -> C#.

How can I get C# related files to appear in this list?

To replicate, open up a C# file, click anywhere with in it and hit ⌃⌥N. Note, I use Rider in zen mode.

Cheers