Ok, from there you should see lots of high altitude as well as plenty of inter-island flights to receive.
I’d be assuming the problem is upstream of the receiver (feeder and/or antenna).
Do you by any chance have an ‘M to F’ SMA pair in your feed?
Instructions unclear, purchased six-mile antenna mast.
I admire your dedication!
Recommend mounting receiver at mast head rather than running coax to the ground.