Phase error reported when calibrating

I am setting up my new Denon AVR-X2700H AV receiver with a set of Bowers & Wilkins M-1 home theater surround sound speakers in a 5.1 channel configuration. The subwoofer I am using is a Rel T-7 sub which allows me to hook up in LFE mode as well as a high-level mode simultaneously.

From the REL T-7 user guide:

“Both the speaker level and the LFE input can be used simultaneously. This means you may set it up for the best possible 2-channel performance sound with your CDs or other stereo signals and instantly revert to using the Sub-Bass System as the dedicated LFE component when watching movies.
This is a feature of real benefit if you wish to play music in stereo mode in the purist audiophile way and also in REL Theater Reference mode with no switching necessary. By connecting BOTH High Level and .1 concurrently and setting your processor to “Large” or Full Range, the best possible performance will be obtained.”

Here is a sample diagram from the REL manual that describes this connection:

Denon’s AV Receivers come with Audyssey’s acoustic correction technology, MultEQ, built in so I went ahead and tried to calibrate the system using the supplied Audyssey microphone… When the calibration process starts to measure the speakers output a phase error is reported in the both the front speakers…

When I remove the REL connections from the front speakers the phase error goes away, I am puzzled now, do I simply ignore the phase error reported? Should I reverse the cables? I am not sure if this normal behavior when connecting speakers and sub in this manner.

I am aware this is not a standard setup for most, but keen to hear if any users have any experience with this to help guide me through this.

Sparechange channel on youtube did a full range center channel setup using a rel sub. Might be what you are trying.