Chewie I too use zgemma h9 blind scan. I have used your user defined settings only increasing the threshold to 17000. And your same settings in the blind scan page
One sat with normal scan would miss many transponders Noticing only horizontal transponders locked.
I then scanned vertical separately and picked missing transponders so now I scan hori and vert separately.
Also with many scan trials a setting of 5 missed some transponders lower settings picked more transponders more channels. Even a setting of 1 picked more transponders than 5. Scans on Mea3 91.5
The ku frequency prob still exists but the above has helped in missing transponders.