• Why clicking on some resolutions in the SwitchResX interface do nothing ?
    Sometimes (and even more with macOS 12.4 and above) macOS returns a list of available resolutions to SwitchResX, but some of them aren't working. In this case, when selecting the resolution, nothing will happen.
    There's nothing that can be done to prevent this, and to avoid selecting it, you should mark it inactive in the SwitchResX resolutions list.

    If you absolutely need this resolution, you may be able to create it as a custom scaled resolution, with one pixel off.

    For example, I was able to use a 1600x900 HiDPI resolution on one of my monitors, that was otherwise impossible to obtain, by creating the custom scaled 3201x1600 resolution (that is one pixel off, but that will not be visible when using the resolution)