More info. If I try to git clone that url from the cli I get an error also:
git clone https://github.com/EsotericSoftware/spine-runtimes.git?path=spine-csharp/src#4.1
Cloning into 'src#4.1'...
fatal: unable to update url base from redirection:
asked for: https://github.com/EsotericSoftware/spine-runtimes.git?path=spine-csharp/src#4.1/info/refs&service=git-upload-pack
redirect: https://github.com/EsotericSoftware/spine-runtimes?path=spine-csharp/src
I thought this might be some LFS thing, but LFS seems to be setup :/