Youtuber Windswept Robert was kind enough to share this story.
For me: Lesson well learned. Never again will I assume the "signal loss" action is set to RTH.
FWIW, I noticed a couple comments stating that he did not have the antennas pointing at the drone. You will get the best signal holding the antennas perpendicular to the drone, not pointing at it. The RF energy radiates mostly from the long sides of the antennas, not the ends.