Looks like your bolt is hanging up on the ejector. What's supposed to happen is the bolt is cammed by the bolt carrier and rotates to unlock so it can be carried to the rear. It rotates until the slot in the bolt lines up with the ejector so the bolt can travel all the way back and the ejector can knock the case out of the extractor's claw and out the ejection port. Now the carrier begins to move forward and the bolt again clears the ejector. It looked in the pic like the bolt was not rotated properly and hitting the ejector on the way forward. I might be all wet but that's what it looks like to me. Are you by any chance using a shock buffer on the recoil spring?
Take the action cover off, remove the recoil spring assembly and work the action with the charging handle to see what is or isn't happening. If all okay, put the spring back in and try it.
There's also a trait of the AK to hang up on the hammer on the way forward, but I've never seen one do it while firing. Spray some oil in there and see how that works if you find it's the hammer.