We had a customer setup a connection from Cloud with an identity provider but they were able to skip the attribute mapping as it was optional. However, later they were trying to use the Federated Group linking feature shown in the Groups tab.

The instructions did not mention that attribute mapping was required and the option was still there for them to use. Well we spent all week trying to figure it out and had to open a support case since it just appeared to be broken.

Hiding this or adding a note in the information screen that said attribute mapping required would help reduce all the troubleshooting here