Private Pilot reported NMAC while descending to land.

Narrative

I was on my return flight from ZZZ to FLY. I was descending to pattern altitude from my cruise altitude of 8500 MSL. At 20 miles from FLY; I made my initial radio call as the area I was flying through is a heavily used practice area. I also had on my position lights and turned on the strobes. I did not see any conflicting traffic on the EFB I was using. At 10 miles from FLY; I made my second radio call announcing I was incoming to join the traffic pattern. At approximately 8 miles out; my EFB alerted me to 'traffic at 9:00 same altitude.' I immediately banked right and pulled up; while looking for the traffic. A few seconds later I heard 'traffic at 12:00; same altitude.' I looked around but never saw the other aircraft. I returned back on course after a few more seconds and landed at FLY without any other issues. I never saw the other aircraft either out the window or on the EFB until the incident. I was not even sure it really happened until I requested the ADSB data. I was told there was 5 to 10 seconds of separation between the aircraft as well as there was a gap in the ADSB data. I looked at the ADSB tracks and the other aircraft appeared to be cruising from south to north at 9600 MSL then inexplicably appeared to descend to my altitude of 7900 MSL at the incursion point. I am not sure if the 'gap' in the ADSB data was just on the ADSB exchange side or if I was not seeing the other aircraft on the EFB due to this issue also. I am not sure what more I could have done to see and avoid the other aircraft. Even if I were to have used flight following; I would have already cancelled as the airport was in sight and I wanted to make my radio calls on the CTAF. My theory is that the other aircraft was following V389 and wanted to cross the ADANE intersection at a certain altitude. I will be working with my CFI to see what more I can do in the future to hopefully avoid this situation again.