Here's what I know. The driller pets will detect any sort of potential collision it may encounter such as walls, pillars, and even other players.
I've experienced similar situations before too, could be due to this.
Events like this definitely have players cluttered together on same maps. Consider changing drilling spot as other players may be blocking your driller pet. Hope it helps
Jewelia IGN: SwiFtREactionzFlamingEternityTITANiumPunch