Hi @fuzzione1
I tested this on a completely unmodded sim version without any add-on aircraft/scenery/etc and it definitely has an issue. I can only change the nav units by clicking the button at the top, and it changes both units. However, neither of the CDI’s change modes from VLOC even if GPS is selected. The CDI button on each nav unit should change the CDI to the matching mode when depressed.
Nice Find! Suggest you submit a zendesk report, and probably use the Bug Reporting format to submit this issue.
Regards
P.S. I’ve included a screenshot from a few days ago while working on an issue with the standard/wheeled 172. Not directly related to this issue, but does show how you should be able to set the GPS/VLOC on each CDI independently. (ignore the green circle, it was just there to show how to select which nav unit you want to use for actual guidance).
Regards