When Tune Stuck in Your Head AA was made passive, it was set to exclude mez. Domination Mastery AA extends single target mez duration, but not AE mez. Tune Stuck in Your Head used to extend AE mez. Bards no longer have a 6s extension for AE mez anymore.
That's ridiculous. Bards have had the ability to temporarily extend their PBAE mez since the expansion they received it.