Creek map, Rare monster spawning outside of the map

Rare monster spawned outside of the map, can't reach it, map is not possible to complete.
I assume the monster is Plague Harvester, they spawn when you walk near their spawn points and then they fly in, however this one seemed unable to fly in, it kept glitching on the minimap as I walked near it

https://imgur.com/Ao2tZIu

Happened to me too on the creek map. I cannot reach the monster. The map cannot be finished. Bug reference number is 1.155.243.114 for this.