No offend but when you say you get an phase error does the correlator go to the center or full to the red zone?
If the latter occurs it may be because of the sound path between DACs and correlation meter. Do you have Phasescope plug-in? That would help to find oud what is going on.
Small amounts of delay between channels can cause phase inverted metering at the correlator for certain freqs, too. When I use delay to spread some mono sounds it´s usual to see the correlator at the center, buncing to the red zone. I use to insert a Phasescope instance at the main outputs in ProTools and I use an external computer with Pinguin Meter for spectrum an XY fast metering. Most of time I use XY metering since it gives more information about these signals.
Please note: When commenting on someone's question or answer, you will not receive notification on follow up comments unless you are mentioned with @Username. So for Andrew Spitz, you only need to use @Andrew