I tried it out, both with my normal ui and with everything but rbm disabled - still the same problem. Arcane Shot, which shares a cooldown (and no one with ES ever uses it so I'm afraid I forgot about it before), also only shows its cooldown the first time.
There seems to have been another undocumented change to LnL, in that they once again removed the internal cooldown altogether. I can't see that really changing anything though. =/