When I use Resource disabler key and add resource to ore harvester blacklist, it still can give that ore, although I get the message about ore added to machine blacklist.
Played as client connected to game opened to LAN on another machine, so I was not the server hosting played
Mod version: 1.16.5-0.11.5

I think I found the problem! It's one I'd had earlier with the Mob Key. Essentially, I was trying to get the registry name of the item but was instead getting its translation key. For example: "minecraft:dirt" vs "item.minecraft.dirt". I've used the search in folder tool to find all occurrences of the text "getTranslationKey" and have fixed (hopefully :) all places that should be using something else. I'll release a fix in 0.11.6.

Done!