Man in motion in field goal formation
 

4th and something on the 22 yard line. Offense in field goal formation. Man in motion, ball snapped, throw by holder (knee not touching the ground) made to man in motion and caught and downed about 10 yards down field. After discussion by referees, and a penalty of illegal something (couldn't hear), ball is placed back on 22 yard line and 4th down replayed.

Can anyone explain this to me?

Sounds like maybe a 10-yard penalty (e.g. holding, "illegal" block in the back, etc.) somewhere at or beyond the 12 yard line after the reception. The play ended at the 12 so a 10-yard penalty would put it back on the 22. Illegal motion would be 5 yds from the previous spot (putting it at the 27) so it couldn't have been that.

Not really enough info to say what happened. From your description of the play it sounds legal. Even if the holder's knee was initially on the ground when he received the snap he is allowed to immediately rise to hand off, pass, etc.
I'm with jblowery. Hmm....

What jb said ... or possibly offsetting fouls and you only heard one on the mike.

Any foul that occurred at the snap (illegal formation, illegal shift, illegal motion, etc) would be a 5 yard penalty and enforced from the previous spot. We can rule those penalties out because the enforcement would move the ball to the 27 yard line.

If the run ended at the 12 yard line, we can rule out any dead ball fouls as those would have carried a 15 yard penalty. The same logic applies to any 15 yard penalties for live ball fouls as there isn't any circumstance that would make the enforcement spot the 7 yard line since the run ended at the 12 yard line.

The penalty for an illegal forward pass and illegal touching (if the pass catcher were an ineligible receiver) would include a loss of down, so 4th down would not be replayed. We can rule those out.

The only options this leaves are 10 yard penalties that would be enforced from the 12 yard line (holding/illegal block in the back) or an incidental facemask by the offense that is enforced from the 17 yard line.

My money is on an illegal block, although I question how many offensive players could have been that far down field on the play as described assuming a relatively tradition FG formation. Essentially I'm picturing this like a jet sweep with the WR receiving a quick toss from the QB and trying to make the corner to turn up field and gain yardage. We do see holds and illegal blocks on those plays, but the difference is that it is usually by a WR trying to help secure the corner for the runner. Out of a traditional FG formation, we don't have WRs. If the player on the end of the line was trying to secure the corner for the motion man as described, I would think the hold/illegal block would have occurred closer to the LOS. I don't think you would draw up this play and have the receivers release downfield and be in a position to block 10 yards downfield if the holder is going to toss it to the player in motion. Using this logic, I still suspect the call was a hold or illegal block, but that the enforcement spot was wrong. I don't have anything to support that other than a hunch, but that is my guess.

Or this. This is actually the explanation that leans on the fewest number of other supporting factors, and as such makes it the most likely.