Hello,
Yesterday I tried to use PolySplit in 4 way split viewport.
I couldn't make it work - only one of the views allowed me to do any operations related to polysplit - mark edges etc. All other 3 views were acting like inactive, no matter what I did (I could still navigate inside view but no actions related to the tool). I could change active part of viewport to another view (front/right etc) and it still worked.

I am using apprentice version (latest 15) and model was just a box.

Any ideas?

Regards

It's a bug. Log a bug report.
Also, after having two polysplit nodes it seems impossible to select points.
It seems that it actually selects the points, but there's no feedback in the viewport.
I say let's wait for H16 and see how all goes.