Are you scanning the entire airband or just local tower and ATIS frequencies?
Howdy Don, I think I recognize you from the PC forums! If you are asking me, and not the OP, I'm scanning different Systems, Departments, and Sites. The airfield closest to me (4 mi.) is the USAF Academy airfield. As I mentioned above, it shows up in multiple "Systems," and although some frequencies overlap in different systems, they are not all the same. However, in one System, they have an Audio Option tag of Search and I can hear those. In another system, they have an Audio Option tag of Color Mode 0 and the only way to hear them is to import to a Favorites List and edit them from Digital to Analog as I've previously described.
I also just posted this in the other recent thread about "Unable to Receive Aircraft"...
------------"I'm new here and just purchased a new SDS100 3 days ago. I ran into the "Unable to Receive Aircraft" issue immediately. After a bit of reading and much troubleshooting, I think there is an issue with the way Sentinel imports from the new RR 2.0 database. As I noted in the thread I linked to above, many (most?) of the analog Air Band frequencies import with an "Audio Option" tag of "Color Mode 0."
My understanding is that Color Mode 0 is for DMR digital frequencies. Since these are analog frequencies, the only way I've been able to listen to them is to create a Favorites List with these freqs., then edit the Audio Option and change the Audio Type from Digital to Analog (or All) which then changes the Audio Option tag from Color Mode 0 to Search. Then I can hear the frequencies.
Perhaps Uniden has not adapted the Sentinel import script to the new RR 2.0 database since it is only a month old. Perhaps I'm wrong - again, I'm very new at this....

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BTW, GMRS, FRS, and MURS freqs. also have the Audio Option tag of Color Mode 0 and I have to edit those in a Favorites List as well in order to hear them.