GRPC schema "directories" not loading

I'm trying to add a directory with a bunch of .proto files it just doesn't work.

The only error message I see in the interface is: Generic error: protoc failed with status 1: Missing input file

The same also happens if I add a folder that contains many other subfolders which eventually have some proto files in them. But I am not sure if the search in folders for proto files is supposed to be recursive.