Ok, so I sorted it out. I now know why this happened.
2 reasons connected together.
Reason 1: the Garmin Glo#1 has a battery connection issue, the device however works without the battery even installed when plugged into a USB port that has 5v output only. Such as vehicle #2.
Reason 2 : Vehicle #1 has a USB output that is multi-voltage auto selected when device is plugged in, so works ok when the Garmin Glo device has a solid battery connection that causes the device & USB port to work at the correct voltage. When the battery connection is lost, the device & USB port can't decide on a voltage, so the port shuts down.
The device I used to monitor what was happening is this handy little USB testing tool.
Hope this helps someone who encounters a similar issue.
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