So I know the conversation is now on when it's best to disclose, but I would like a clarification. If I understood your problem right, you have no problem getting answers when you don't mention poly, and you have no problem getting answers from mono people even if you mention poly, but poly people don't respond if you mention poly?
That seems a bit weird. One thing that comes to mind is that maybe because you have a committed partner they fear you're only looking for sex on the side, or that you're hierarchical and have tons of rules, etc. I used to talk in priority to guys who had a committed partner, because I'm interested in committed relationships and to me that showed they could have them, but half of them seemed to actually be cheating, either because they admitted it in some ways (oh yeah, we're poly, but my wife doesn't know) or because they had very weird "you can never see my wife or if you see her don't mention that we're dating" kinda rules.
And then the rest was very hierarchical. So it was all along the lines of "what do you mean a relationship? I have a wife already. I just want sex. You have a long-term partner top so that's what you want, right?" or "Of course we can have a relationship! You'll be allowed to see me from 9:30 to 11:30 once every other week, but first my wife needs to "interview" you to make sure you're okay. Then you can only give me blowjobs, and I can't interact with your vagina in any ways"
There was only one guy who seemed to have similar ideas as a did, and we turned out not be a match (we became friends though so that's still good). So I got a total of zero dates out of OKCupid (and I had to be the one sending messages to every single one of the guys, too).
It's possible people worry you're like that. Not sure what you can do about that, but hopefully someone will eventually give it a chance and talk to you to figure out if you are.