When I initially open TBB in Whonix I see the Whonix placeholder screen with links to amongst other places this forum. When click on the forum link, it takes me to the version 3 type hidden service link for the forum. When I click on the Login button, after filling out my username and password upon hitting enter, I am taken to the standard (not the hidden service) forum web page and I am not shown as being logged in yet. However, if I close that tab in TBB and go back and again click on Forum on that placeholder page, I am taken to the version 3 type hidden service for the forum and it then shows I am logged in.
Is this what is meant by two factor authentication? I joke. The login issue happen all the time though for me.