For some time I could have forgotten about the sync problems, now they seem to be back again with the OS4?..
It looks so. I use Logic (9.0.2 and 9.1.1 recently) Quite often I must start playback several times for the Virus to sync properly or wait a couple of measures for it to "catch up" with the rest. It often starts with MUCH lower tempo (for instance about 40 instead of 120 or similar) and after four or more ticks it hurries up to catch up the tempo. It can be best heard in arpeggios that do not match the drums for instance... horrible...
It's quite annoying, specially that the problem didn't exist with the latest 3.xx os release.
It helps sometimes to turn "send midi clock" option in Logic preferences and turn the metronome on to speed up syncing.
I didn't change any of my setting that worked sssooo well with TiOS 3.xx.
please help...