Replay shows that hovering over the Dauntless Bodyguard shows the Priest it's protecting (the other one is greyed out) at all times except when something is on the stack - that's unfortunate.
This is not a bug. You can only cast Fierce Retribution at sorcery speed due to Plot, you're not allowed to pay the alternate Cleave cost since it's been plotted, and there's no legal target because no creature can be attacking during the main phase.
Our preference is to support Duel Commander separately (when we are able to do so), leaving Casual 1v1 to use the multiplayer ban list.
We have no interest in reviving the old Commander 1v1 format and its need to maintain a separate ban list without Studio support.
We are doing some work in the background to correct some of these frames, currently targeted for a few months from now for the whole project to finish. It is unlikely we'll correct the reminder text piece unless new Fuse cards are made
We will not have native Mac support due to how the initial architecture of the game was built in Windows. There are workarounds available that you can search out on the Internet - we don't provide direct support for Mac use.