Micro "skipping" some transponders during blind scan ???

I have been having some problem with my micro, it sometimes "skips" some transponders on a blind scan.
I can go back and do a manual scan on the individual transponder(s) and it will then scan in. It's kinda like the Signal/Quality levels are not coming up fast enough and the micro just skips over them.
Sometimes it scans the whole satellite to end up with no program found, I can then open the transponder list, verify that signal and quality is there, have it scan that transponder and it does then find the channel(s).

Would it possibly have anything to do with the fact that those transponders and channels are already scanned into memory?
If so, shouldn't a blind scan indeed be "blind" and scan whatever it finds, regardless?

But, I'm thinking the problem is most likely that the signal and quality levels sometimes "stick" and sometimes are slow to "pop in".... any ideas on why that happens, what causes it?

Thanks,