What’s the rule about “none was” or “none were”?

"Rule"??? Puleez don’t use that word with me! Some linguist pronounced grandly a “rule” that none must be treated as singular: “none is...”. Then along came another linguist who said, “No, none can be either singular or plural.” Once again the GA says, “Record your guideline and use it as you deem appropriate.” None of her children were boys. (Plural) OR: None of her daughter’s whims was reasonable. (Singular)