I don't understand at all why you say that you've checked and know that you're on the right sat??? Ie what do you mean when you say "for AMC21, G3 is at 100"????? This doesn't make any sense to me.
On another topic, looking at your hardware, it looks like you're using a Corotor feedhorn, and if so, you should be setting your receiver to STANDARD (ie 10750) NOT "Universal , 9750/10750" .
With that setting, you're likely to find two things when you do a blind scan, (1) get duplicates when the receiver THINKS that it's using 2 different LO freqs, and (2) some of the freqs will be wrong. Ie if your blind scan gave a signal at 12162 and 11160, that is likely to be the same signal, since your 2 LO freqs are 1000 apart. I presume that the 12160V30000 is an actual hit, but there isn't any such freq on AMC21. That freq does appear on other satellites however, typically for data transponders. I really suspect that you're on the wrong satellite.
Also, I'm curious relative to how you're changing polarity? I assume that you're using one of your 4DTVs to change polarity, but I wasn't sure. Also, again assuming that you're using a Corotor feed, I assume that you also have C-band analog capability on the dishes you're trying to find AMC21 on, and that you used one of your 4DTVs, sending the dish to G14 (G5)? If so, are you seeing the scrambled ESPN signals on ch-9 and ch14? Are you receiving Ku on other sats, because the example you gave above is C-band. If you do see Ku, do you see the Ku at the same position as the C band version of that sat?
Reason for last 2 questions is that if the feedhorn isn't at the proper focal point, then Ku will not focus at the same point that C-band does.