Minecart with Command Block did not update

Please describe the bug you experience in more detail

RE:Marcono1234
Nothing else, just place a Minecart with Command Block then open it.

What happened? What did you expect to happen?

RE:redstonehelper
Add Repeat mode and "Aways Active" mode

Invalid, this is a feature request.

The bug happens when you enter information into a command block minecart, close out of the GUI and right click back into it.

Not what this report is about, per the reporter's comments, it's about the lack of mode and activation buttons.