Anyone have thoughts or suggestions to try?
Yes: please fill out a bug report with a debug log, per these instructions:
https://chirp.danplanet.com/projects/chirp/wiki/How_to_report_issues
Describing the issues sounds nice, but the meat needed to actually see what is wrong and do something about it is in the debug log. I don't have an F6 so I may or may not be able to help with that. I do have a 92AD, which works for me, but I have to see that debug log as well to have any idea what's going on.
Also, the F6 and the 92AD are not the same cable, at least on the face of it. Are you using an adapter to go from the 92AD multi-pin connector to speaker/mic jacks and then putting those onto the F6 cable? If so, I'm surprised that works at all. I've only ever used the 92AD for programming with the data cable, so that's really all I can reproduce here.
--Dan