The main reason for black eyed peas that aren’t cooked all the way is that they are old.  If your black eyed peas have been around in a package for too long, they take longer to cook. If it happens, simply replace the lid onto the Instant Pot again, shut the pressure valve and cook for additional time. You can repeat this process until they are tender.  Jus note that if the peas are really old then they may actually never fully tenderize.