Supports spawn underneath map out-of-phase in Crown of Keldegonn, forcing wipe

oracle

Observed behaviour: A lone support occasionally spawns at or underneath the map edge when the dragon lands on the platform in the last phase. Associated mechanics (including sound effect and buff icon on boss) apply and continue to play. Often the trial is not finishable because the support cannot be targeted or even killed by AOE attacks.
Expected behaviour: The dragon lands on the platform without additional supports spawning. Further supports only spawn and perform their mechanic during the appropriate phase (i.e. when other mobs spawn).

This seems to happen at random during the last phase of the trial, and I have no reproduction steps to offer other than to reach the last phase of the trial.

Example (see support underneath map and players):

nitocris83

Escalating - thank you!

oracle

In case it helps, another example, with other adds spawning with the support.