Yeah I'm having similar issues. I can't count how many times someone ran up behind me to stab me while I had amplify on and I didn't hear a thing. At other times I can hear people from damn near across the map.
Also I swear sometimes things don't show up with sitrep. I'm still dying by too many IEDs while running this perk. It may be the color scheme as you suggest causing me to just not see them on the map at times. I dunno. Sometimes I feel like they didn't show up at all.
I've noticed on some surfaces even someone without dead silence can be difficult to hear close up. Like limited amounts of places on the map carbon I think it's called. You can hear people accross the map on sand, but then in one of the buildings on cement they don't make a sound, even while springing. This could be what's happening and it needs to be fixed. Also what's the deal with this in game music? 3 minutes to go and i can't hear anything for 30 seconds cause they decide to play some ambient music to set the atmosphere. Wow i just cling to the edge of my seat from excitement every time I hear that music play. But in all honesty, no, i go sit in a corner and hide cause i can't hear anyone. 30 second gf to 2 perk points. Just as bad if you join a game late.