Multi channel to mono - Cubase artist 12

(for some reason) I can all of a sudden only record to the left side of a stereo channel and the other inputs are “not connected”. While I attempt to sort this is multichannel to mono available in Cubase Artist 12? Google returns it’s in the project dropdown but it’s not there. Is there an easy - read: not export and reimport file tapdance - way to do this in Cubase Artist. Thanks in advance for any info