It would seem - IC2 Classic causes/doesn't play well with new updated version of Dragon API and RotaryCraft v17a of v17b.

As per comment on reporting issue to Reika site.

C2-Classic-Spmod{0.0.0.0} [IC2 Classic Detection Helper] (IC2Classic Version 1.2.1.5.1.jar)
It certainly seems so - the cause lies within the fact that the entire ISemiFluidFuelManager is an always-empty dummy (returns null and an empty HashMap respectively).
For my own setup I wrote a small Patch to overwrite it with an actually working one.

Fixed on Reikas Side:
ReikaKalseki/Reika_Mods_Issues#1446

Thanks - I really appreciate your work. I really couldn't use IC2 prior to finding you mod - just too much grind.

I'm playing and your working - thanks