Cassindra's Chrous Of Clarity Not Working
 

As the title said, it ain;t working on both display effect and mana boost.

That be all.

On you, a bard, or other players?

Both other player and I. Mana ticking boost should be at least 7, it was ticking 2 and 4 something like that.

you the bard are immune to any sort of means for mana acquisition, so you will always be stuck at 2/tick sitting.
Manastone, modrod, potg, c2 etc all refuse to work on bards. also, it's worth noting a couple of things:
1) the amount of mana one gets from pulsed mana songs only gets amplified by the bard epic
2) the amount of mana scales with bard level, from 5 to 7 for that song and
3) client displayed mana/hp values displayed in the ui are notoriously wonky sometimes ticking up or down haphazardly, complicating "measurements" of regen rates.
I suspect a combination of bard mana immunity and thing 3) to be responsible for your predicament.

You're right it is now only 2 ticks, and I'm sure it was working before?, at least it was ticking 2 and a 4-7. A shaman in group said it isn't working for him and I thought he meant that Cassindra's Chrous Of Clarity icon not showing, but did not ask to check ticking before logging off.

What about lvl 55 Cantana of Replenishment?, I hope it work!.

Both songs should work. I don't recall Cassindra's (or the other pulsed mana song) ever showing as an icon in your buff bar, but you should see a text message in your combat log each pulse telling you it's applying to you.