Looks like I may have found the problem….. current Asus XG32UCWG monitor firmware MCM301 was recently updated with MCM104 (MCM304 - once flashed). Reported that it updated the VCP Protocol for HDR flickering. ”Flicker-Free HDR: Optimized DisplayWidget Center (VCP protocol) to eliminate screen flickering during HDR transitions.” A few flash attempts later (8Gb FAT32 USB Drive - 16Gb USB Drive did not work) look like things are stable post update. So far testing seems stable at 164Hz @4K