This is great news!!!! Exactly the same to me.OK, So...I just received a personal M1 MacBook Pro from work. I haven't installed much on it. But also recently received a refurbished Nav VI from Garmin due to mine going wonky on my trip to Florida a couple of weeks ago. I've got a bunch of USB cables hanging about and the first two I tried behaved exactly the same as what you are seeing. I downloaded both Basecamp and Express. With the first two cables, I could see the GPS had power, but it wasn't putting it into the disk mode. The third cable I tried, bingo! The Nav VI unit came up with the connected screen and Express told me it had located a new device and asked if I wanted to connect to it.
I suspect it's your cable at this point because I can verify that it will connect properly.
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So you also changed the provided garmin cable? and which dongle?