So, I promised an update when I got a new card. I ended up purchasing a PNY 64GB XC I. I finally got to use it yesterday and I had NO problems. None of the stopped recording problems or a clip locking up and not finalizing. It worked every time and I recorded 11 clips, some very long, some shorter. The PNY micro card replaces my SanDisk 64GB. Both are equally fast cards.
In fact, I seem to have a new problem...right in the middle of flying and recording video, twice I got a "Disconnected" warning from the GoApp. It just stopped working and went gray. Once, it was while I was landing and I could not stop the recording. The clip did not finalize until I landed, powered everything down, changed batteries and restarted everything. The clip then appeared to repair itself. But I supose this is a problem for another thread.