The issue with purges with hyenas has been posted several times. This is the link to the latest post about it. Purge creating hyena cubs that you have to find and kill to start the next wave
It’s basically a known issue with Hyena purges spawning pups randomly for some reason also and “breaking” the purge.
Not sure about the “Bask of Lizards” purge. I’ve had 2 or 3 of those and 2 of them worked fine to the end. One broke because someone built a house on top of one of the spawn zones for part of the purge so the ones there spent the rest of the purge trying to get out from under this house/beating on the foundations. 