(IdleAnims + scale bones) strange limits

[Vedamir]

I have an ongoing overhaul mod project and have some problem with it. I've built a character customization system, based on "scale bones + idle animations" approach, like one used in "Growlfs Body Resizing Mod". Because of high combinatorics price, I add several idle animations in an array then play them all one by one, to make certain combined changes to a character. At least this is how it's intended to work :)

The problem is that the idleAnims silently (w/o any error message or anything) refuses to deform a mesh from some index of that array (the clips are all "played" at least according to TDT info, without any error; so that's definitely not about script) while the index of "stuck" idleAnim can vary too. That stuck index is not totally random, but I can't clearly determine the conditions of that. In other words, there is always some limit on a count of scale bones that can be properly animated, and this limit is dependent on many conditions like the the existence of currently equipped item the mesh of which is skinned to some non-default bone, animations involving some custom bones and maybe something more.
The same behavior, involving exactly my added scale bones and corresponding idleAnims affecting that bones - is repeatable in CSE on idle animations preview with any NPC.

All this situation feels like there is some hardcoded limit on something like "bone path string" or some other value, related to bones(their count) affected by keyframes. The longer chain and/or count of animated bones is, the more is probability that it'll be affected/stuck. Plus, the "limit" is also pushed(negatively) by custom non-scale bones if they are animated when idles are applied; in that case the "space" for my idleAnims shrinks even more.

I'm poking around that issue for more than a week already, with no actual result :(

So I'm writing this post at least to know whether someone met the described bug or some similar behavior...

Edited October 13, 2019 by Vedamir