Dimming (flickering) lights

[mikeames]

I am in agreement with beanland

New washing machines use a VFD. If so, the VFD could be rich in harmonics. Dimmers are SCR based and vary the turn-on point based on voltage. These harmonics could be affecting the dimmer. If not a VFD washer, the load variation during agitation may cause the current to vary and the voltage to dip. Again, some kind of interaction. Your voltmeter may not sample and display fast enough to see the pulsations.