Pasting that post as the answer.
Posted Sep 18 in Studio One 4 by nathanholliday
I ran into a major latency issue a couple weeks ago, and I reached out to Presonus tech support about it. My input latency was sitting at 23.1 ms when either my UAD Apollo or Apollo/Lynx Hilo was set as the IO device. Nothing would change it, we tried everything. Block size, etc etc. Even spoke on the phone with a guru named Brian (shoutout to you, my dude. You're tops in my book), and we couldn't quite get our heads around the issue.
AS IT TURNS OUT there is another form of delay compensation inside the UA Console application. If you are experiencing massive latency in Studio One, you must turn this off.
I will admit, it is frustrating that UA does not support Studio One. I did not have latency issues in PT, but as many of us here can attest, I have #madetheswitch and I'm not trying to go back any time soon (barring critical tech issues such as this one). Seems silly, like an "oh duh" solution, but man I've been dealing with this for weeks. Now it's fixed and I'm just so stinkin happy.
I hope this helps someone!