RE: Unexplained loss of control
really sounds like a 2.4 lock out. how many satelites are you runnning? ive had and seen this same issue. 20' off the ground hovering, cockpit facing me, plane 25' in front of me. bam! lock out!! had it happen twice. ALL 2.4 systems have blinds spots. You might have found one due to the orientation of your rx. Do you check your rx after you turn it on to make sure you have a full connection and not a parial aka blinking light?
from your descriptions, inputs and volt feed. I just dont see anything else being an issue.