During my trying to troubleshoot my spindle sped PWM not working (which turned out to be user error), I clicked the box in the PMDX plugin config to allow the PMDX-411 to update firmware. It reported that the new version was the exact same one as before, but I let it update anyway. The update went off without issue.

Now, whevenever I jog (key or arrow mode), it instantly hits a Motion Underrun error. I tried maxing the buffers out and it made no difference. I have been running this machine for over a year now and never saw this issue before so I don't think there's anything wrong with the PC. Literally the only thing I did was let this firmware update run. Any ideas?