The team forums were messed up when Etsy switched to Lithium's software. It caused a few problems, mainly with Teams and they have never been corrected. I doubt you're searching incorrectly, but a lot of promo teams are older and haven't been active for years anyway.
However, you should be aware that promo teams are basically a waste of time, not to mention that fav'ing without buying is detrimental to shops and listings.
