Mac OS Installer GUI is rendered in a mask

Hey, I'm stuck at the start of the Mac OS installation. I can not see the complete UI. I'm using clover and I guess I didn't not include something that is related to the graphics card. I have tried the "Inject ATI" option, but without any luck. My clover config is based on this sample config (link down at the bottom of the page)

My system specs:

- i9 9900K

- Gigabyte Z390 UD

- Sapphire NITRO+ RX Vega 64

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Here is a photo of the \"masked\" UI

My USB mouse and keyboard are working, but I can't see anything.

Maybe someone here has an idea on what I could try. Thanks!