Influencing Scarab of Interference boss spawning in first room of Elder guardian fight

When using a Scarab of Interference in an Elder Guardian map, an additional boss appears in the first section of the fight. This boss will not reappear in the second or third sections of the fight, and is instead lost forever (as is any loot they drop if killed prior to the transition).

More bosses also spawn in the third room, and behave properly.

Expected behavior: additional boss(es) should only spawn in the third section of the fight, similar to the Maven's 'Up the Stakes' ability from Destructive Play.