Ok I have a thought... It is a bit of a band aid but if it works...

The top flex watt seems to be set deeper than the other one you posted. Is it??

If that is the case that could be the issue heat dissipates quickly in air you might try adding a spacer under it to raise it up some. make sure the spacer will take the heat I personally would use pvc but I have some laying around a thin bit of plexy might work just make sure it won't get too hot and cause a fire.