Bug? Group cue part.

I don't get this and it feels like a bug.

When I'm typing [Group][cue][part][2] I get the selection with the channels from the group. However if i want to continue typing and for example remove channel 1 from that selection, Im all of a sudden getting the whole cue grouped instead. 

I couldn't find a way to group a part and then continue working with that selection. 

The workaround to make it work for this specific case was [Group][cue][part][2] {Make Manua} [Select Manual]. 

I'm on a Apex 20, tried on my computer and sam thing happened. 3.2.6 build 29.