I think this is a bug, unless something major changed since Dire's Spotlight. I copied Dire's wall spell to ensure I had a working code: http://i.imgur.com/RPPVp1W.png Then place the spell on a loop cast bullet and fire. The first column is built, but the spell does not loop.
MC 1.9 forge #1804

EDIT: This is not broken in r1.1-45, nothing more to see here.

I seem to be seeing this again. Posting this as a comment because it seems like the same kind of symptom.

Using AutoRegLib-1.1-4, Psi r1.1-44, Forge 1.11.2-13.20.0.2224 (and I think I didn't uncheck the mercurius thing, so that's there as well) under Java 8.

FML log: http://pastebin.com/cVyfQWyC

In a world with more mods installed, I reached the loopcast tutorial legitimately, tried it out, and it never looped. Specifically:

I made a basic spell that output the loopcast index with the debug trick. It only ever output 0.0.

I then made this minimal setup. Constructed various permutations of CAD, loaded the debug spell into a loopcast bullet, and cast it. It only ever fires once.

I just now thought to try with a spell circle bullet. That output 0.0 through 19.0, so looping itself, and the loopcast index selector, work.

Spell, for reference: http://imgur.com/a/xiFge

Is there anything I need to do differently to make the loopcast happen, or should just using the CAD with the loopcast bullet selected be sufficient? It's sufficient for the spell circle.

That spell doesn't work for me at all, even manually setting the loop index. Could you try a different loopcast spell?