There's a difference between "fixed" and "improved". It's totally possible that there was on issue on Kunos side that still exists, the PS4 update improved it but didn't necessarily fix it. Also, they were working on the fix before the PS4 update so they might have had no idea this update would help with the problem. As you can see some people have said it's better, some have said it's the same as before, so there's still something on Kunos side that needs improving. Knowing Kunos, they'll always continue making performance improvements.