Thanks friends. Maybe I don't have always perfect timing in triggering fills but I don't have these issues with my Ketrons, Rolands and Yamahas. As far I can remember, these issues had been going for a while now since my early Korgs.
I know there's no perfect keyboard, but this Pa1000 is almost for me except for this glitches.
Ketron SD90, Korg Pa1000,TC Helicon Play Electric, Fender Sonoran Guitar, vArranger, Bose S1 Pro, Bose L1 Compact, Aiwa Exos-9