In-folder credentials are not listed in the SCM section of the shared library.

Steps to reproduce:

1. Create a folder
2. Create a shared library in the folder
3. Configure the SCM section
4. Create a new credential in the folder (I created one matching the SCM url type, git@.... so SSH Username with private key, save.
5. It is not listed in the dropdown

The same credential is listed if it is created at Jenkins level.