Install of Olarila 10.15.5 was a success! Thanks so much for the updated image. I'll send another donation your way.
Some of the changes since .3 included control for the new Mac Pro monitor, and I'm wondering how .4/.5 is working with those changes using our graphics and monitors.
When first booting into .5, the monitor looked very saturated and bright, and when I found the HDR option in Display prefs, I found that the HDR gave the monitor a flat look with less colour and saturation. After another reboot, the monitor looked like it did with my 680 card on .3, but after trying out Sleep, the monitor went back to being bright and type on the screen looked pixelated and not 4k sharp. It seemed like there were 3 different modes that I saw with the only control being the HDR option.
I'm using the Sapphire Pulse Radeon RX-580 8G connected by Display Port to my LG 32UD59-B 4K monitor.