No luck here either. I wonder if just stretching the spring a little would help? I have four different mag releases and the only one that's giving me a problem is the rifle with the PWS T3 release on it. That combined with the variance of sizes of the mags has given me feed issues by not holding the mag far enough forward in the magwell ( only happens with the 25 rounders). I don't think it's the release lever, it just feels like a weak spring. Guess I'll try stretching the spring today and report back.
OK, I stretched the spring, tried 6 different kinds of bulk ammo and had no issues except for one. The Winchester 555 in a plastic feed lipped 25 round BC extended mag would still stovepipe. Other ammo worked fine in it. I have had feed issues with the Wins before. The mags fit much tighter than before.
To the OP, I normally use 2 of the Tri-Mag setups with absolutely no issues. My problems were just with the extended mags. My observation is, side to side movement is OK, fore and aft movement not so OK. Hope you get yours figured out.
Edit: I should mention that before I stretched the spring I was having issues just like yours. After the spring stretch, the jamming turned to stovepipes, but only in that one BC mag with Winchester 555.