The quest involves marking three Ankhet Transports, each of which has three stealthed Ankhet Infiltrators underneath.

When the Infiltrators are killed before marking the Transport, the Transport should despawn and be available for reuse later.

Failure to kill the Infiltrators (either by bug or by player ability) causes the Transport to be marked without despawning, eventually leading to a congestion of Transports in this semi-stuck state.

Proposed Solution
Option 1: Marking of the Transport forcibly despawns the Infiltrators.
Option 2: The Transport cannot be marked while its associated Infiltrators exist.