Aloha and Welcome! :wavey:
In my opinion, the problem with the Trade Assist matches is that it just shows matches, without factoring in whether or not the potential trade(s) might be fair and balanced. The same problem exists with filling out the Trade Assists; you can just fill out the pins that you are offering in exchange for the pins you want to receive, and unless *you* take the time to make sure the trades are fair and balanced, there is no system guaranteeing that they will be. And if you are accidentally sending out unbalanced trades, that could account for why you aren't getting any responses.
My suggestion is to invest some time and become familiar with the pins you want to trade for and trade away (values, trade statistics, etc). Then instead of just 'throwing things at the wall and hope something sticks,' spend time putting together your requests, making sure you consider them fair and balanced. No guarantees that this will work as some people just won't respond no matter what (unless they want to trade), but you may end up getting better results.
I hope this helps and good luck with your trades. 🙂