I made two short trips to the south and east side of Philly since around the 1st of the year. During those trips, I saw at least these talkgroups active:
Philadelphia (P25) (30 talkgroups)
South EMS Dispatch (South Medic) (37 hits / 254 seconds / avg 6 seconds)
South Fire Dispatch (20 hits / 143 seconds / avg 7 seconds)
North Fire Dispatch (8 hits / 47 seconds / avg 5 seconds)
North-East Division (2nd. and 15th. Districts) (5 hits / 23 seconds / avg 4 seconds)
City-Wide Traffic Operations (10 hits / 56 seconds / avg 5 seconds)
East Division 2 (25th. District) (3 hits / 11 seconds / avg 3 seconds)
Unkn (6 hits / 25 seconds / avg 4 seconds)
Tow Squad / Impound Lot / Taxi Enforcement (13 hits / 82 seconds / avg 6 seconds)
North-Central Division (22nd. District) (7 hits / 34 seconds / avg 4 seconds)
Central Division (6th. and 9th. Districts) (5 hits / 42 seconds / avg 8 seconds)
Pump Operations (1 hits / 4 seconds / avg 4 seconds)
North Division (14th. and 35th. Districts) (2 hits / 11 seconds / avg 5 seconds)
Administration (5 hits / 29 seconds / avg 5 seconds)
City-Wide Special Events 1 (2 hits / 47 seconds / avg 23 seconds)
Housing Police Operations 1 (5 hits / 22 seconds / avg 4 seconds)
South Division 1 (1st., 3rd. and 17th. Districts) (6 hits / 40 seconds / avg 6 seconds)
KPHL - Fire Operations (Engine 78) (1 hits / 10 seconds / avg 10 seconds)
West Division (16th. and 19th. Districts) (11 hits / 50 seconds / avg 4 seconds)
Prisons- Institution Operations (5 hits / 19 seconds / avg 3 seconds)
City-Wide Administrative Operations (6 hits / 43 seconds / avg 7 seconds)
East Division 1 (24th. and 26th. Districts) (5 hits / 17 seconds / avg 3 seconds)
Parking Enforcement and Boot Squad (7 hits / 43 seconds / avg 6 seconds)
South-West Division (12th. and 18th. Districts) (5 hits / 19 seconds / avg 3 seconds)
KPHL - Emergency Operations 1 (2 hits / 19 seconds / avg 9 seconds)
North EMS Dispatch (North Medic) (15 hits / 74 seconds / avg 4 seconds)
City-Wide Emergency (7 hits / 73 seconds / avg 10 seconds)
26th. District Tactical (19 hits / 132 seconds / avg 6 seconds)
25th. District Tactical (2 hits / 18 seconds / avg 9 seconds)
Far North-East Division (7th. and 8th. Districts) (3 hits / 29 seconds / avg 9 seconds)
Prisons - Institution Operations (3 hits / 14 seconds / avg 4 seconds)
According to the information on RRDB, there are two simulcast sites -- which one are you trying to monitor and where are you in relation to that site?
You may want to program the system twice - once for each of the two sites - and see if that makes any difference. You should be able to (and I recommend) programming only the control channel (red) frequency (or all control channels - red and blue).