When reviewing maps outside of performing an activity (Round-Trip course options, past activities), I cannot touch to pan but instead have to use the incredibly slow side-button method. This has been described in multiple other forum posts:
Touch function for zoom/pan for maps - Forerunner 955 Series - Running/Multisport - Garmin Forums
Map panning is very slow when reviewing a run - Forerunner 965 - Running/Multisport - Garmin Forums
However, I'm starting to wonder if instead of a bug this is just a feature that hasn't been implemented. It would be nice, though!