[pulsar124]

Not that it should be affecting anything, but you don't have to run the AS plugin before starting music.  On Estuary as soon as you enter the music visualization screen AS will start.  Only because I'm not sure if we're talking about the same screen (you mention going into full screen mode which often just means hitting the slash key to have Kodi take the entire screen), I'll go through the steps that should work.

1- Open Kodi and go to the music area.  Select some music and start playing it.
2- hit the left arrow key (either on a keyboard or your remote) to open the sidebar.
3- In the sidebar use the down arrow to go all the way to the bottom so that the pause icon is selected (DON'T CLICK ON IT)
4- Use the right arrow to go over to the last icon (it looks kind of like four arrows pointing out) and then click on it

That should open the visualization window and start AS.  It may take a second or two, but you should start seeing your override folder of images randomly displayed.  If you don't, I'd need to see a debug log.  There's a link in my signature on how to turn on debug logging for Kodi.  In addition to that, you also need to enable debug logging in Artist Slideshow. The toggle for that is in the Advanced settings for AS.  I wouldn't leave AS debugging on any longer than needed to capture this log, as AS is VERY verbose in debug mode and can really cause your log file to balloon.

P.S. I've never tried Kodi on a TV using Andriod TV, so hopefully what I gave you works. 

Thanks for the detailed instructions! I am pretty sure I did click on the correct icon to go to the full screen mode (I'll double check that), so I'll be collecting the log info as you described.