Maybe it’s my bike, but radiator cap only seats fully in one direction. Even though there’s two fingers on cap and it appears it can go on in one of two rotations 180-degrees apart, only ONE of those positions will allow full clicking into 2nd final fully seated position.
After bike cools off, try unscrewing radiator cap, note its position, remove, rotate 180-degrees and reinstall and see if it goes to 2nd-stage to fully seal.
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