I've been denied for this game from Ironsource as well. In fact, 2 of 5 ironsource offers have been denied, coincidently the big ones....

Also, my friends ahve been denied by ironsource. I avoide them now like the plague.

Personally I've had 100% success rate with tapjoy.

Just yesterday I finished a 400+ tokens game (King of Avalon), and got my tokens instantly.

Fybers offers are just bad. Too low and geneally just some pages full of ads.