I agree it's strange. So, questions... What time of day did they disappear? Where were they when this happened? Usually the other chickens will act strange if they've had a predator scare, like avoiding the area it was. What type of area do you live in? What type of fencing and coop? When there are only feathers, maybe a cat of some kind, though they won't usually go after full grown birds. What kind of trap are you setting and what are you baiting it with? Dogs would have killed the whole flock and left the bodies behind. Different raptors have different MO's. And that doesn't sound like weasel, raccoon, opossum, or anything I can think of. There should be more evidence. Seems like more evidence would be around if it were a mountain lion or bobcat as well. All though I see your location, I don't know the area to give better suggestions.
I probably would have taken the Jubilee.
If it was a predator and not a thief, they WILL be back for another meal. But for 2 birds to disappear at once..... Maybe a family of hawks or something like that, who's teaching their young to hunt.
Have you posted to CL or facebook in the lost animal section and maybe indicate they could have been taken? We have had luck with those communities, even in finding animals that became deceased already. but even then, it's good to have closure. Honestly, in your shoes, I would probably think about it non stop until I had resolution. And talk about suspicion every time I saw someone walk by! Did your roo crow? Maybe post like "new crowing in your neighborhood" and offer a small reward like $25. Also, you might be checking the farm and garden section on CL to see if someone is trying to sell them. If I was posting for them, I would do... farm & garden, pets, and lost and found sections of CL. Sounds like theft if they took a male and a female SFH!

So check every chicken ad you see. Dang losers!
Sometimes when you set a trap it may take a few day before they hit it because it is something new in the environment so they are cautious. But once it's a regular sight they may try. Just be aware that if they get trapped and somehow make it out, they will then be wise about it. Are you prepared to dispense of the predator if you do catch one, by a means other than relocation which is ALWAYS a bad idea and illegal in most locations?
Note, this is an ongoing, learning process for me as well. So as much as I try not to spread misinformation, if there is something I confused or misrepresented, kindly let me know please... to all posters.
Rooting for you and your flock!