If you have an instrument channel with a VSTI creating either a MIDI sequence or arp on that channel, or choose that VSTI as MIDI input for another instrument track - You will find that the midi timing is unstable, jittery in a random fashion. And also, curiously, you will find that that Plugin Delay Compensation does not function at all when using an insert introducing latency, such as Cubase’s “multiband compressor”.
If you were to record the MIDI notes onto a part, and have the notes play from there instead, then the timing becomes stable again - and PDC will also work again.
Is this a bug? This really disrupts my workflow and it means (as just one example for you) that I couldn’t use the UVI Falcon internal sequencer reliably = the timing becomes too sloppy for mixing, and PDC does no longer work.
I’ve tested and this timing issue is precisely the same, when using any other plugin MIDI sequencer, it is not exclusive to Falcon. The result of MIDI coming from a VSTI either on an instrument track or routed to one is that Cubase plays back the MIDI information with random timing of up to 2ms (!) random jitter. If the MIDI is recorded, the timing becomes solid, and PDC works again.
Cubase 12 @ 44.1
MOTU midi express XT