Can't get hyperpixel 4 to rotate

I’ve fitted a hyperpixel 4 touch screen to my Raspberry Pi 4. I’m using a new image of the 32 bit OS, it installed updates when I installed it. I’ve added

    dtoverlay=vc4-kms-dpi-hyperpixel4 

at the end of config.txt and the display works but it’s stuck in portrait. I added a line

   dtparam=rotate=270,touchscreen-swapped-x-y,touchscreen-inverted-x

after the dtoverlay line but the display doesn’t rotate. I noticed that with this line in place, when I reboot the shutdown screen is rotated, but it’s back to portrait when it starts up again.

The instructions say to disable the hyperpixel4-init process but doesn’t say how to do this, I’ve done some searches and I can’t find the answer. Could this be what’s causing the problem? If so, how do I disable this service?