Jenkins allows case insensitive authentication but the matrix authorization does not account for that. For example, let's say my username is sam but I log into Jenkins with Sam.

When the Jenkins admin adds Sam to project-based matrix authorization strategy and I log in using Sam I'm still not given administer permissions.

I was only able to realize this by visiting http://jenkins.example.com/whoAmI and realizing that my login and internal username was a different case.