Laptop - can't rotate the screen

I have a weird bug on my Hackbook.

It's a Dell Inspiron 15 7000 (2-in-1), model 7586, with an i7-8565U and Whiskey Lake UHD620 graphics. My screen's 15.6' and FHD.

Because of the high DPI, I've used one-key-dpi to patch the EDID to enable proper scaling. It thinks it's an iMac display, but I've also tried with the Macbook and LG display EDID options.

In the macOS display settings, I can see the rotation settings for my external HDMI display, but not for the internal display. I've tried holding cmd+alt as I open the display settings, but nothing changes. Rotation is listed as supported for the internal display in the System Information app.

Some googling led me to the fb-rotate tool, which lets you rotate screens from the terminal. It worked flawlessly on my external monitor, but when I tried it on the internal monitor, the following happened:

- Both screens went black

- The apple logo and progress bar appeared on the internal display for a few seconds, as if it was booting, but the apple logo was red and had a square background which was another shade of red

- I was taken to the login screen.

After I logged in again, the internal display had rotated, but the scaling was reset so everything was tiny. The scaling options in the display settings disappeared, and the rotation settings appeared. If I set the rotation back to normal, the settings changed back to normal - the rotation settings vanished and the scaling settings came back.

Does anyone know what's going on here?