Confirmed Megatron Post Combat Convert Trigger doesn't work

[CoffeeStain]

He's in vehicle form, you attack, sac an artifact with say 5 cmc, kill a 1/1 of the person you are attacking and 4 damage tramples over to the player. He converts to his main form, hits them for 7 damage. Post combat, trigger goes onto the stack which should let you decide to convert him back to his vehicle form and add colourless mana equal to the amount of damage dealt, but it just goes on the stack, then disappears and nothing happens.

 

[CoffeeStain]

Game 1 #824637120 Event #255381036

 

[CoffeeStain]

Do I need to provide more evidence? Don't really want to join a commander game with a broken commander and upset the game for other players, but if needed I can.

 

[Angeliana]

This should be fine, we will let you know if we need more information. Thank you.