Thanks! Horizontal NDS preset is now works.
FYI, I’m using Nightly build updates on my Steam version of RetroArch because otherwise RetroArch doesn’t let Online Updater menu appear on Steam version, and I’m actually testing everything first on a non Steam version clean install of Nightly RetroArch build. NDS_4K Vertical preset presists with same error on this RetroArch setup as well.
Also I have to add a note for dummies that they should set Simple Presets options to OFF in order to properly get full content shader .slangp file instead of just a reference shader. It took me some time to figure out the problem when I was keep getting reference shader file instead while following the guide instructions step by step
A heads up information about this option in the guide would be helpful for other newbies.
Take care, man and thanks a lot for your guidance here. Appreciated