Hmm, I'd believe it being a Unity bug, because without HideInspectorStuff(), there's no call to HideFlags whatsoever... I may just have to hard-code it so that whenever Unity tries to make a build (onpreprocessbuild?), the Fix() code is called...?
I'll take one more look soon before resorting to that method though, the fact it may be related to an initialization even will help! Thank you so much for your patience and help!!