Hi There! Thank you for reaching out.
1. I'm on Studio One 4.5.4.54067 WIN x64 from September 12th 2019.
2. My OS is Windows 10 Home version 1903, build 18362.418
Both of these apps are rented by Splice. I don't think this affects anything but I thought it would be worth mentioning.
3. After digging a little bit deeper, it appears that pigment's entire tempo sync is about 12% faster than the clock in studio one on all BPM settings. I learned this by setting up a 2 bar loop with a pigments arp preset and a 4 on the floor kick drum. The arp consistently finishes a full beat ahead of the kick after two bars. This pattern holds after testing on a 1 bar loop and a 4 bar look, the discrepancy is a half-beat and two beats respectively. I tested this on a patch with lots of vibrato created from an LFO with the same result, so it looks like this problem is affecting the entire plugin, not just the sequencer.
4. I conducted the same tests with my other softsynth, ANA 2, and Studio One's stock polyphonic analog synth, Mai Tai. Both worked perfectly fine, so this issue seems to be isolated to pigments.
5. As mentioned earlier, the problem persists when I use a kick to compare the recording.
6. Quite the contrary actually! The problem instantly vanishes once the track is rendered to audio, and the arp plays perfectly in time with the kick. This only seems to be an issue when triggering pigments in the DAW.
7. The problem actually seems to go away when played outside of the first bar. Afterward, if I move the sequence to the first bar, the problem stays absent. This is great news but I have no idea why that is the case.
8. This issue occurs with or without a loop.
Thank you so much for your help! I look forward to hearing from you soon.