Just finished a 90 practice session with Piano V2 on my KeyLab61 mkii controller. The random cut outs of the left audio channel has been plaguing me without resolution for a while now. @LBH and @MajorFubar have been helpful with investigative comments and guidance.
But today, this annoying issue of speaker cutout did not occur a single time!
Yesterday I updated several software things via Arturia's Software Centre (ASC) and Piano V2 was among the updates.
This updating procedure is the only trigger or differing factor I can think of occurring in the past day or so. I've changed nothing on my end. I don't know if this problem-free situation will last or not, or whether something was done with the update that purposely or inadvertently fixed it...or what?
Anyhoo, a happy Piano V2 camper again! Fingers crossed it lasts.