Reported: Right-clicking the MMOPS First, Second or Third-person Mode skill shows "Require a special effect to use the selected skill/force".
Found: The message comes from the game client itself. The 1.5 client marks these three skills as needing a special effect that nothing in the game grants, so it refuses the cast before anything reaches the server. No server change can reach it.
Fix: a change to the client's own data, set out under Camera Mode Skills here: https://oldschoolops.com/docs/games/rf/15/client-data-fixes/
Back up the file before editing it. After the edit, casting a mode switches the camera. On servers newer than 0.2.1, casting a different mode replaces the active one, and Ctrl+click on the active mode returns the camera to normal.
If anything here still goes wrong after the edit, please file a new report and mention RF15-129.