I recently used the SwitchResX app to fill out a 1920x1080 space with a Boxlight digital projector.
At least, I think I did.
I followed the steps from the tutorial explicitly as I was having the same problem with the truncated 1920x540 resolution.
When I completed all the steps, there was no change, I was still seeing a 1920x540 image on the projector. However, when I went into the Apply Display options in System Preferences, I noticed that a bunch of new options had opened up.
Does that mean my custom resolution preset actually allowed for more options in the Apple Display menu? For some reason, I thought the changes I made in SwitchResX would be applied automatically.
I guess I'm just wondering if my tinkering with SwitchResX did anything or if some other unknown variable changed the options in Display options.