I don't know anything about prepping acorns for food other than reading about it a while ago but my first thought was "did you properly remove the tannic acid?" I've heard, that done right, acorn mash and flour are quite edible (though different) if prepped properly. A pre-acriculture staple of many peoples.

"Oak: The Frame of Civilization" by William Bryant Logan sketches out the process but I read it a few years ago and didn't take notes.