Yeah that's the real pro tip right there. Those thin coatings just don't cut it for bio stains, they let everything seep back up. Went through the same headache with a dog that kept finding the same corner. Switching to a heavier duty seal was a total game changer, no more chasing old smells. It's one of those fixes you only learn from getting burned.
Let that area dry out fully for a day or two before you even touch the sealant. A good thick coat, let it cure, then hit it with a second one. Rushing that second layer is how you end up back at square one in six months.