The NVRAM is a difficult thing to design, since the response of the controls has to be tolerant of system supply voltage variations, minor ones, of course, while sensing "out of range" Vcc over the longer term, and disabling controls on account of it. There are NVRam's and there are BBRam's, The latter are just Battery-Backed, while the NVRam's have to have control signal management. Unfortunately, the nomenclature is not universally accepted/understood.

For some time, I've suspected that these reset issues are related to the amount of capacitance on the Vcc. I say this only because several of my boards have several sizeable (e.g. 330 uF) cap's on Vcc, and switchers are not known to "like" capacitive loads. Perhaps the reduced size and cost, coupled with the increased capacitance of physically small cap's is a contributing factor, as it would certainly impede the rise-time of Vcc.

RE