So I've done a bunch of trap outs, using the cone method, all with reliable success.
I set a trap today and the bees are reacting abnormally - they've been clustered all over the box and the cone, even a wad of them at the tip of the cone (gotta go check it tonight to make sure it's not plugged). There's a little coming and going at the entrance, but I've always seen them take to the trap box within an hour or so.
Possibilities - it's a lot hotter today than when I've set previous traps. I used a frame of open brood and eggs with heavy honey and smaller brood patch because we are in the dearth.