Seems to be an issue with Proton Wine's d3dcompiler_46.dll. installing the Windows version through winetricks makes it work.
Olympia Rising seems to be rendering the title screen with the latest Experimental build and seems to be playable now, closing since the issue is fixed now.
Compatibility Report
System Information
I confirm:
Symptoms
I can hear the sound of the game and the buttons do seem to work, the screen just isn't displaying the title screen at all, making the game unplayable. I also did some regression testing and found out that the last proton version that displayed the title screen was 5.13-6, after that, 6.3-8 and onwards was when the screen stopped displaying anything.
steam-295910.log
Reproduction
Just start the game up with Proton Experimental and notice how the screen stays dark, but the music still plays and the sound effects still go off when pressing buttons.