Im unable to select a mirror or connected board column in the group view option

I have an old board that has a first column named TYPE with thre type of inputs only - field, office and other. In a new board I have connected to the TYPE column and choose a TYPE for each single item (more than 20). All good so far, but I need o group my data in the new board, by the ТYPE column, but that will now show up among the list of grouping options. Any fix or shortcut for that?