I'm in the new mombasa streets, and i'm in a part where there are flashing police cars around me with their sirens going off. it says the beacon is near but there is nothing by me. I've done the levels Tayari Plaza Uplift Reserve Kizingo Boulevard and ONI Alpha Site
If you turn your visor on, there should be something highlighted yellow near by. Go by it and pick it up.
I don't know the level names but is it the one with the sniper hanging from cables above you? Or have you already done that.
That's in the main storyline making the Flashback of Romeo happen. (Romeo's playlevel) Like LockOn said, it should be a yellow outline, and the Cars Flashing should help point to where it is, the way they're faced they usually tell you where it is. Also, it might be in a place where you need a certain amount of Audio Logs to get to like in a Supply Cache.