2010 MacPro Tower - 32GB RAM, macOS 13.13.3, AMD RX580
Blender 2.8 (July 4) with Todays download of ProRender from main page
Open blender, add cube, add cycles material, switch to ProRender. - .blend file attached
1 Render with both CPU and GPU checked = crash and quit
2 Render with only CPU checked = crash and quit
3 Render with only GPU check works - see attached image
Note 1 - Unable to create a ProRender material when 1 and 2 are true, however I can create one when 3 is true.
When the "add material" button is pressed Blender crashes and quits.