Something you said gave me an idea, when you asked if the folder that won't keep its sort settings was linked to an external drive. I realized after a second look that it was linked to my C:\ drive - but to the system folder "desktop". I thought maybe being linked to a system folder might have something to do with it.
So, I moved all those files to a new folder in a different location - and lo and behold - the portal fence now keeps the sort settings!
HOWEVER, later I discovered a problem when playing around with the View settings for each portal fence and that is if I set the view settings to Medium or Small icons - it will only show one icon per "page". In other words, it will show a small icon at the top of the fence and then I have to scroll and as I scroll it shows one icon at a time.
One portal fence is set to disply the contents of a folder that has a couple of hundred files in it. So, to only see one at a time makes it pretty useless.
If I set it to view Large or Extra Large icons it displays as it should. But I really want to use the Medium view setting and that one just doesn't work.
Large Icons Work Fine:
Anything smaller than Large - looks like this: