is there any i need to do before for the exotic class item quest

[desert tapir]

after doin a overthrow nothing spawns

[umbral venture]

Once you kill the final overthrow boss in each area wait around

A message will appear above your super bar saying " A secret keeper is nearby"

I recommend looking at a video to find where they spawn as it does not change

Kill each one then go back to the Blooming and look for a pillar of green light shooting up into the sky, towards the refraction

Then a timed event happens, you need to kill two mini bosses and take an orb back to two plates, you'll see where they are via indicators on your screen

do the two orbs on the two plates and bam, mission unlocked for all your characters.

[desert tapir]

that message never appears for me

not the witch in the caves