I'm playing Rhye's mod (Rhye's of Civilization Expanded, 1.23, random map), but that forum is not very active lately, so I'll post this here, too. On more than one occasion, I research Fission, but no uranium shows up. About as often, aluminum shows up before I get the tech for it. I've straightened this out by going back to a previous save, but I'm tired of losing so much work.

Use Worldbuilder to erase the "problematic" resources until you have researched the techs you need to see them. Then, place them back using Worldbuilder. That is the only idea I have. I hope I am some help.