Hmmm I have gotten this answer from Nicholas who has invented Loginguard:
Our system plugin does some checks on every page load. If you are not logged in no action is taken. If you’re logged in and there’s a server side session flag that’s you’ve gone through 2SV no action is taken. If you’re on a LoginGuard URL no action is taken.
Otherwise we check if you have 2SV enabled on your account. If not we set the flag and that’s the end of it.
Otherwise we check if there’s a previous URL stored in the session. If not we save the current URL. Either way we redirect you to the captive login page of LoginGuard.
This is also how Joomla’s privacy component works. In fact I invented the captive login technique for Joomla and then Joomla itself copied my technique
Regarding your problem it depends on how CB’s plugin works. If it performs the redirect onAfterLogin you have no problem with LoginGuard. If it tries to do the redirection on the page load AFTER logging in it will never work as LoginGuard makes its own redirect and after 2SV redirects you back to the original page you were before.
As I explained, the same holds true for Joomla’s Privacy component. So if CB’s plugin doesn’t work with LoginGuard it also wouldn’t work with Joomla’s Privacy component, therefore CB would need to make some changes. Maybe ask them how they implement it?
If I deactivate Loginguard the CB auto action redirect works, but not when I activate loginguard. I believe as Nicholas writes, this would be the same problem with Joomla 2factor activated ?