You need to configure Melodyne plugin as a tempo based effect. You will find this option under: Plug-In Manager > VST Audio Effects > Melodyne plugin > VST Plug-In Properties



[Track vs. clip]

Melodyne plugin works as a track insert. Operation as a clip based effect or being used in the "Process" menu are not supported.



[Setting of window size]

If you set the window size of Melodyne plugin in the manner described in the User Manual, this (initially) has no effect; so what you have to do is enter the same settings in Sonar's plug-in manager; then remove the plug-in; and finally insert it again.



[Bypass]

If in the course of playback you switch Melodyne plugin to bypass mode and then back, Sonar and Melodyne plugin will no longer be in sync. If that happens, you should stop Sonar briefly before restarting it.



[Precount]

If you are recording with precount switched on, all instances of the playback of Melodyne plugin will be offset by the amount of the precount in relation to the other tracks. Rather than using the automatic precount, then, you should start the recording somewhat earlier by clicking manually at an appropriate point in the timeline.



[Timeline]

If you click in the timeline while playback is running, Sonar unfortunately does not pass this information on to its plug-ins. As a result, Sonar and Melodyne plugin will cease to play in sync. To avoid this, you should stop Sonar first, if you want to jump to a different part of the song.