Yeah, from what I can see about that mod is that it replaces the coal resource on Vulcanus with a special resource. Check the other tab of the Resource Monitor to see if that resource is hidden there. Otherwise I'd need more info or screenshots.
Also be advised that "I see coal" is not a visual mod.
Okay Update it was possibly an one-time glitch and I was unable to replicate it, seems to be working as-intended now. Sorry for the confusion.
