Do you have a specific edition that you want vs what the other person has? I am not 100%, but maybe that is an issue.
No, I have it set so that I would take the card from any edition and I also activated relaxed matching.
My bet is that trade opportunities are based on where both you and everyone else is willing to trade. If, for example, someone from the US is only willing to trade within the US, then they shouldn't show up on your trade opportunities. Change your setting to Worldwide (or continent) and you should see more matches. (Edit Profile > Trading Information > Will Send)
That could be it, maybe people have it set so that the would trade only locally so they don't apear, but I feel like that should't preventing from showing up, deckbox should make so that the opportunity apears and tells me that the person only wants to trade locally, who knows, they could be persuaded.
What I've notice the last few days is that some people use the page incorrectly as they put the card they're willing to trade as inventory instead of tradelist. So that's another factor