Good day,
Well, the question title asks it all. I spent the better part of a couple of days trawling the net, searching within Unreal Slackers for references to this particular item (I found 1 reference by the way but as a bug report for something unrelated to the question) and fiddling in the engine to try and understand why this is kinda half-implemented in blueprint.
As far as I can see it aims to pull information from the currently playing animation sequence. Now there have been questions before about pulling info from playing sequences from the skeletal mesh, and that only works if you are not using an animation BP selected within the mesh, but only “Animation Asset”.
Why am I asking this? Well, I’m using animation sequences for my locomotion at the moment, and I would love to pull information from the currently playing sequence such as “current time position” and “currently playing asset” stuff that appears within blueprint requiring this “AnimSingleNodeInstance” as its input.
I can create a variable, but can’t set it to anything, casting to the animsinglenodeinstance fails from the input of all things except the mesh where it returns “none”.
There’s no blueprint create class for this animsinglenodeinstance either, even though some documentation (the little there is on this) suggest it inherits from animinstance.
2 ways to get the info I would like - move to montages for everything, or control the animation within the character blueprint, manually setting the assets into the mesh, neither is a favorable solution.
Obviously this looks C++ related and I was torn with which section I wanted to post to, but as its majority in blueprint, I chose that.
So I’m hoping someone out there can shed some light on this interesting node as I would love to implement it into my game development journey.
Thanks for reading 
W.