The problem I think could be that animations b001-b008 are not the right type of animation. Even with the default FNIS idle animation (which is thing like shoveling dirt, sweeping broom, etc.) the animation is broken and does not loop correctly, so I think it is a problem with the current version of FNIS. Regardless, FNIS has added support for o animation (animated object animation) to include anim object since a while ago I think.
So, just rename animations b001-b008 to o010-o017, and they should work fine (because current version of FNIS spells has slots to go up to 18). Also, go to anim object files included (meshes/animobjects/FNIS) and rename the anim objects b001-b008 to o010-o017 as well.. otherwise you will end up doing the sexy time with a broom LOL (yes it happen to me -.-).
(should also add that, if you do this you do not need to run generate FNIS for modders. If you ran it previously and got no animation, you will have to delete all FNIS files and install FNIS + FNIS spells again completely. I hope it makes sense)