Try having a coop friend who already has Old Betsy unlocked drop it for you (even though you already have it unlocked in the shops) and see if it pops. Have the #3 pole equpped before picking up coop's #4 Old Betsy pole, as I'm pretty sure it won't prompt you to pick theirs up if you have the same pole equipped. My coop gf had #3 unlocked but never fished for record fish & it popped for her as soon as she picked mine up. idk if this will work for you, but who knows with this pretty broken game :/
I have the same issue, no 4th rod even I got blue ribbons over each fish in the boards. I'm also stucked in progress to 66% even almost everything is completed. And I have still couple of keys in my inventory even those keys have been used already.
Even starting of new game did not solve this 66% progress issue. I'm pissed off with this...