Immortal monsters in Matlan Waterways

I'm going through the campaign in the dawn of the hunt softcore league and just encountered a weird bug in Matlan Waterways, where two normal rarity River Drakes with the minion tag resurrected over and over again. I encountered them near the beginning of the Waterways and killed them countles times, but they got resurrected every time and chased after me untill the very end through the entire map. All of the other monsters acted normally. It wasn't really too bad, just slightly annoying but I decided to report it either way.