Just FYI, I had precisely the same issue with a Garmin 2750LMT immediately after its last software update.
It stopped being recognized on two of my three Win10 machines for several days. One day I managed to get it to be recognized on one of them and another software update was applied, and it's unusual for Garmin to push multiple software updates in rapid succession. After that update was applied it was recognized again. I think they introduced a bug, and an intermittent one, that they then fixed.
It was really frustrating that the device was recognized long enough to apply that initial software update, which caused it to be flaky about being recognized after, which blocked map updating once the maps had been downloaded since the PC couldn't communicate to the device anymore.
Generally a Garmin unit, once plugged in to a USB port, never goes to sleep during an update process. I knew that something had gone wrong when it did so during the time when the maps were downloading but it was still connected to the computer.
Brian AKA Bri the Tech Guy (my website address is in my profile) Windows 10 Home, 64-bit, Version 1709, Build 16299
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