A buddy and i tested OPK in a public event, for a couple minutes, just to see if anyone would even know. They did. They like, instantly knew. And didn't like it.
So, a player limit has been added to OPK. If you're in a group of four people, it will work. What that really means is if there are only four people in your render distance, OPK will work. As soon as anyone else is near you, it will stop working. This is to help prevent the use of OPK at high pop public events. I've attached a clip of it from my stream yesterday.
There is no flexibility in this, there has to be a limit or too many people will get caught with it.