Okay, but if I turn on the redirect then both the joomla login module and the CB login module throw a TOO_MANY_REDIRECTS error. If I turn off that redirect then both of them work and if I deactivate the plugin entirely then both work as well. Doesn't that suggest there's an issue with the redirect of the CB system plugin?
I don't normally use both login modules, I only made a Joomla login module to try and get MFA working once I started getting the errors after upgrading to 4.2.2 from 4.1.5. Usually I only use the CB login module and would like to use MFA with it, but I'm having the issue described in this thread. Also, I don't want to hijack this thread if I'm not supposed to, should I open a new one describing my situation?