@modaltb Interesting, that's good to know they should be identical (what I assumed), that's why I was puzzled when it didn't seem to work.
On VOXL Flight we're using port J13 and it's always worked perfectly without issue the first time we're wired up a new unit.
I have not tried starting via the command line, but that's a good idea to try.
My best guess is a loose connection in the wiring somewhere or a pin not making good contact on the board. If it should be working the most obviously problem is user error on our part or something not making contact properly.
We ended up sending them one of our VOXL Flight units where we knew it worked perfectly each time instead of using the Flight Core because they were in a rush to get things working.
Thanks for the suggestions!