I had the same type of drop from the big ring on my previous Emonda. Ultimately it boiled down to a misaligned chainring pin (they're designed to pick up the chain and "help" it onto the big ring). The pin would grab the chain, but not release the chain when it should. So the chain would appear to have made the shift onto the big ring, but the pin would continue to hold onto the chain until the pin reached the 3 o'clock position, at which point the tension on the chain would pull the it off the big ring, completely bypass the small ring, and dump it right into the frame.

Dunno if that's what happened to you, but I'd take a magnifying glass to the inside of the big chain ring to see if you've got any misaligned pins, damaged chain ramps, or a bent tooth. It'd be pointless to get your frame repaired because this will happen again unless you find and fix the problem.

HazeT is this your Workswell 066 frame?

Spyder Composites in the San Jose area can have that repaired in a week. They did a repair on my Raleigh with both chainstays cracked at the bottom bracket. This is what i would consider to be a minor repair.

Yes sir, I'm considering another one but I'm concerned about the 2-3 weeks delivery time for the frame. I gave up on looking for a disc frame since those brifters costs a fortune.

I will take a look at that, could very well be. As I mention this is the 2nd time it happened. After the first time when I got home I re-adjusted the derailleurs. I didn't even crossed my mind to look at those. I'm honestly considering just put some nail polisher on and go ride and see if I can make it happen again.
Do you think a bad chain line could also cause the problem? when I put the bike together I completely neglected looking at chain line.

If you've got a bent tooth, damaged ramp, or misaligned chain pin, you're going to drop your chain regardless of the chain line. The thing about this kind of problem is that it's damn near impossible to replicate, because you have to shift at exactly the right moment in exactly the right conditions to hit that pin in the right spot. I had hundreds of miles between instances.

I will go the easier route and replace the crankset :). I had one that came with the power meter and a still sealed one that came with the rest of the groupset.