Pi uses a sophisticated algorithm to allow proper phasing adjustments. In terms of latency/delay Pi uses a lot of latency for properly adjusting/optimizing phase.
Some hosts doesn't cope well when a plug-in notifies such big latency/delay.
1. Make sure delay compensation is enabled. please refer to your DAW manual for further help on how to set up Delay Compensation correctly.
2. Close and Reopen the session/project after adding Pi.
Many hosts adjust the delay compensation properly only after closing and re-opening project.