The monk spell "Essence Font" no longer exists as of 11.0. This is causing an LUA error, as the spell_names lookup function now returns a nil value for that spell.

BugSack:

Plexus/Statuses/Auras.lua:493: bad argument #2 to 'format' (string expected, got nil)
[string "=[C]"]: in function `format'
[string "@Plexus/Statuses/Auras.lua"]:493: in main chunk

Locals:
(*temporary) = "Buff: %s"
(*temporary) = nil
(*temporary) = "string expected, got nil"

fixed: 95d55c9