["The Council Cargo", Mission 1 (Villain: Ouroboros 10-15)]

"When participating in this timestream, your power will be limited to level 10."  Indeed, I dropped to level 10.

 

The first mission is "Get shipping info & clear base" - which shows in the mission list as being at level 12.  Meanwhile I'm set at +0.  Makes the mission slightly more challenging than expected!  I tried leaving the task force and picking up the arc again, resetting notoriety... For some reason the mission is just set to a base level of 12 despite you being power-limited to 10.

 

After managing to finish the first mission, the other two missions in the arc spawned at the proper level.  It's strictly the first one that's incorrect.

[Arcane Bolt and the June 2nd, 2021 patch]

I don't know if this is a new bug or not, but Arcane Power also procs during Ouroboros missions (and presumably other Exemplared content) when you're below the level at which you picked Arcane Bolt, and thus can't use it.