They might just not be as sensitive as the main speakers. Did op give us a speaker list? If so I missed it and really don't wanna dig back through 20 pages to find it... lol.
Also
@OldAndSlowDev, did you manually adjust your mains so they're at 0.0? I would leave them wherever YPAO had them. The idea is to have them all playing the same volume at mlp and room interactions and positioning can result in some differences.