• If you happen to use side-chain compression on one or some of the tracks and both the compressed track and its side-chain input source have Pi on them - it may cause sync errors. To resolve this, simply duplicate the side-chain source track to create a dedicated side-chain trigger track without Pi.
  
  

•  Make sure Pi is not inserted on any Group/Aux/Bus/FX or Master tracks and the tracks that feed them at the same time, for example, your Snare track and the Drum Group track - this will cause Pi to feedback internally and may cause Sync errors as well.
  
  
• Try setting your audio buffer size to 512 samples and in Pi's settings (click the cog-wheel icon to access them) increase Pi's Lookahead Buffer starting at 250 samples and increasing incrementally up to 550 samples and see if the sync errors are gone (make sure 'report latency to host' is enabled).