Why is the buy button only appearing for some products?

Dear All,

I got a problem as buy button only showing for some products, but add to cart showing for all, Show dynamic checkout buttons is activated though, don’t know what’s going on as it was just ok before adding contact us section to some products, tried to remove it, but no help , help please

Attached images for two products ,one showing buy button other not, both with dynamic checkout buttons active.