My UCL tier has spontaneously reverted to 1 from Mummy Dust levels at some point during a long encounter.
(Dirgesinger with 10 levels, Dirge of Awakening, and Lasting Inspiration)
Transitioning to another server allowed Mummy Dust level summonings on the destination server, but returning to the previous server resulted in an immediate reverting to tier 1 again.
This is a devastating thing to have happen in the middle of a long dungeon or voyage.
A pack of baby unbodied and a will-o-wisp is what I got instead of my dread wraith and orb wraiths.
Relogging and completely exiting and re-initiating the game did not fix it.