Sorry for the delay..... Unfortunately, Garmin's helpdesk has been nothing but a waste of time simply due to their blanket answers and excuses for improper cables, settings, etc.. I tried my older and new data cables including Garmins oem cable. I.M.O. and after a lot of research, I believe the problem is Garmin's Intel based software. I "didn't" have any issues with connection/communication with my 2016 (Intel) MacBook Pro. Garmin's software is Intel based which doesn't communicate with Apple's Silicon.
I do understand that Apple's Silicon architecture is somewhat new. Yes, there needs to be updated software made available from other manufacturer's as well. My problem along with many other's is that Garmin won't even state if they're even working on updating their software to include Apple Silicon. Instead of being honest, they opted to throw every excuse they can in regards to why us new Apple M1 Mac owner's are having problems; Incorrect cords, improper settings, the need of having to use powered hubs..... Just to name a few. Great advice if you're on an Intel based computer but, this isn't the case.
Bottom line, Garmin would rather "TRY" to BS all of us...... than give us the truth of their current inadequacies.
I don't know anyone that has a new M1 Mac in regards to giving it a try. I will report back if I ever get up and running "if" Garmin comes up with new software. Thanks for the help, appreciate it.