There are various .dds files used for the UI and other stuff.
They all seem to be compressed in some way, but the game only loads my files when I generate mipmaps and turn off the compression.
This results in a big filesize, so I want to know, how can I compress my .dds files so HWR loads them?
The image is either a red placeholder with an error message in the log file or just black.
Fixed it myself.
When exporting with GIMP, generate mipmaps, set the compression on DXT1 (or DXT5 if you need alpha) and tick “Use perceptual error metric” in the advanced options.