I use the puppy kong stuffin, but not the liver paste flavor..we usually get the peanut butter, the puppy paste that's white, and sometimes we use plain old cheddar easy cheese
Did you check the expiration date on the can? The only other thing I can think of is that it's separated from sitting on the shelf too long-try shaking it up and see if that helps? You might try contacting KONG about this and see if they have any advice or will refund/resend you a new can.