Could say many things here and someone will agree, someone will disagree. When I first learned to connect with coyote (after working on other species)
it was all about two primary things.
1) Location of your sets
2) What you do at the set (odor issues, lure/bait/urine, wind direction, set type, etc...)
You can do some things poorly and still catch some coyotes but trying to be on target
and catch all of those passing your area is more difficult.
If you aren't even getting them investigating as you put it, are they within a few feet, 20 or more feet or hundred yards or more?
If you see them on the trail cam and you see their tracks on your trails you should be able to be on location
where they are moving through which takes the "location" factor down a bit.
However the smaller location ie. corner of a trail, slight rise in terrain or drop, etc... places that might funnel, are still important
if not more important than just being along the trail.
Decision on what lure/bait/set type etc... are all very very important, again you might grab one or two in something thrown in
but bedding your traps solid, having a set that gets them looking and committing is also part of it.
Anyway, I'll leave it for others to smooth out my rough spots, but you get the jist, tell us how far off the coyotes are from your current
sets and are they breaking stride or just passing on through.