PTB latency modes not working as expected

Hi all,

I’m seeing some odd behavior when presenting sound stimuli and using PTB latency modes. I’m synchronizing the sound presentation with a trigger output for an EEG experiment and when using Latency mode 3 I was getting a lag of about 100ms with respect to the trigger being sent. I verified this using an oscilloscope. Troubleshooting the code I changed the latency mode to 0 to see what the worst performance looked like and to my surprise this had sub millisecond accuracy. In summary, Latency mode 0 gives me better timing accuracy than latency mode 3, and I can’t get my head around it.

Has anyone experienced this before?

I am using Win 10 64-bit Education edition 22H2, and a new installation of psychopy on python 3.8.18 via anaconda.