Energy Drain will only tech burst on enemies that have shields up. Not sure if that's a glitch or intentional, but it basically can't tech burst if the enemy has no shields.
Sort of wrong.
Energy drain will set up a tech burst on anything, but it only has a 3 second window to be detonated. You have to be pretty close to 200% and relatively close to the enemy to prime with ED and detonate with Incinerate due to its travel time.
Energy Drain can only detonate on enemies that the shield drain effect works on. This means fire explosions from Incinerate -> ED will only happen on synthetics, shields, or barriers.