I got a little problem with the arpeggiator of Omnisphere when used
in Cubase (I hope everyone understands my decription ;-) :
I have created a little base-line using the arpeggiator and I noticed
that the first note does not sound in a arp-line when the note starts
exactly at the bar. If I let the note start just a tiny fraction earlier
it is being played...
The one with the system-time for MIDI-events would not help as this
just helps to "tag" the incoming MIDI-events with the correct time when
they are received from the external MIDI-device. This problem is solely
an internal issue between Cubase & Omnisphere (the notes I tested have
in fact been "drawn" in the sequencer with the mouse ;-)
The other suggestions with the track-delay works only for the first
time the arpeggiator is triggered on the track - for each new note
the first arp-step is ommitted...
It may not help at all but it can probably give a hint:
I encountered a somewhat similar problem in Live7. While looping a sequence driving an arp-patch the first note of the loop was choked. After slightly shortening the length of the last chord in the loop (which ended exactly at loop end before editing) the problem was solved.
Glad it worked for you as well. On a side note: this issue was not new to me as it happens with other synths, too (e.g. Firebird/Tone2). However, I learned some day that it's a good idea to distribute bulks of (midi)messages on the timeline when possible...
I still think that this is not correct behaviour and should be looked into on Spectrasonics side (I have send them an email with a sample-Cubase-project showing the issue & one with your fix applied)
I don't feel this is "incorrect behaviour" of Omnisphere at all -- it happens to me all the time if I have MIDI info ("on" notes) overlapping in Cubase (maybe other sequencers as well). I was working on a project just yesterday (using M-Tron in Cubase) and couldn't figure out why the first note of a MIDI clip wouldn't sound -- I looked closer and saw there was the same note overhanging from the previous clip in the same spot -- just shortened that note, suddenly no more wierdness.
Anyway, I'm *so* glad you found the solution to your problem -- I love Cubase so much, actually, but I've had so many wierd timing things over the years -- how many hours have I sat staring at the settings pages, just praying for some clue as to what suddenly went wrong, LOL...
(Thankfully I've been running smoothly for at least 4 years now!)