The option hides (unless shift is held down) items that come from Windows and the Windows context menu system, i.e. everything except Opus-specific commands. Anything that appears when you right-click a file in Explorer, more or less. "Windows items" for short, and lack of a better term.
The file type editor in Opus shows you all of these "Windows items" as well as the Opus-specific commands, but if the option to "Hide Windows items..." is on then you'll only see the Opus-specific commands.
If you want to keep the option on but also force Opus to show the commands in your screenshot, the thing to do is add new context menu items which run the same commands, setting them to the Run an Opus function (not supported in Explorer) type:
That creates duplicates of the commands which are Opus-specific and will only show up in Opus. (Of course, if you then hold shift or turn off the "Hide Windows items..." option, then you'll see both copies of these commands.)
(Unless it's something you're going to use really often, it's easier to just hold shift when you want them, or other hidden items. You'd only need to do this if you want to hide items by default but force certain items to be shown all the time.)