This is sort of an edge case, but with mods that add multiple variants of ore such as Emendatus Enigmatica, ores are unified to andesite ore instead of stone.

The default ore within the mod has the id emendatusenigmatica:x_ore but for some reason this isn't prioritised over emendatusenigmatica:x_ore_andesite.

This is not a bug.
There is no "default ore". Items/Blocks can be added to tags but these tags don't have any order.
Maybe I can add some sort of item priority config option in the future but that is very low priority.