Jumping to solutions when your innovation team is still in the problem definition phase is hasty, but so is ignoring people's ideas.
That's where a parking lot of ideas comes into play.
Create a section on your brainstorm board titled, "Parking Lot."
When a product idea pops up outside of an ideation session, jot it down in the parking lot.
People will feel heard and comfortable moving forward and you'll be at ease knowing no ideas went uncaptured.