The Mixars Primo requires a firmware update to firmware version 1.13 for it to work correctly with Serato DJ Pro 2.1.2. This firmware update includes improvements to the jog wheel touch response.
You can find the Mixars Primo firmware 1.1.3 update on Mixars website under "Firmware For Primo" here: https://mixars.com/support-download/
We recommend re-calibrating the jog wheel touch after firmware update, instructions outlining how to do this can be found here: https://mixars.com/download/primo/primo_touch_calibration.pdf
NOTE: If you try to use the Mixars Primo with Serato DJ Pro 2.1.2 using an old firmware version, the pitch sliders on your controller will not work. Simply update to firmware version 1.13 to fix this.