Animations "decay" in 3ds max 2018?

[Dark_Ansem]

I'm not sure how else to explain this: some models in Skyrim have a baked-in animation, a simple one, such as a staff with a rotating orb.

 

I managed to import one in 3ds max 2018, the "apocrypha paper twister 3 model".

 

However, for lack of any better word, the animation "decays" after a little bit, in 3ds max 2018 with this plugin.

On the other hand, in NifSkope it looks and loops fine.

 

Any suggestion, please?