Have you followed the FAQ about setting up the columns etc. that you want?
A few details will be different if you're still using Opus 9, but the general steps remain the same.
Flat View has its own folder format. (At least in current versions of Opus. I can't remember as far back as Opus 9 or when this was added.) That might be what's causing the change.
The command is using STYLELIST when it should be using STYLE.
One resets all pages (tabs) and the other only resets the current page (tab).
I doubt you need styles for anything if the aim is just to change which columns are turned on in Flat View. Edit the Flat View folder format in Preferences instead (assuming it exists in Opus 9).
There is a FAQ on where they are, but you shouldn't edit them by hand.