update: to replicate this behavior one doesn’t need to install python or pil: attached is a simplified example using only c# script from animation controller
the ouput looks like this :
but should look somtthing like this:

webPmaker_simplified.gh (10.1 KB)
edit: also animation control outputs more frames than defined by the slider; which in my case calls the python script twice
edit2 : I modified the animation control script and it now outputs the right range; viewcapture is still empty though
webPmaker_simplified_v2.gh (11.9 KB)