Players locked in combat with the forces of Hell may be encountering a strange bug with a bug — or worm to be more precise.
During Helltides, the large Hellworms that spew monsters from their maws may be leaving behind 'invisible walls' that players are unable to move through. This is due to their collision boxes not being removed after they disappear back underground.
Blizzard is aware of these bugged bugs.
As the invisible walls can affect all players, this can potentially create problems if a Hellworm happens to leave their collision box in a particularly unfortunate place.