Same problem: iMac Pro (2017) happens when I go away, screensaver kicks in or when I activate the screensaver (with password lock) by moving my mouse to a hot-edge 2 external monitors (left, right) via USB-C/Thunderbolt to HDMI connectors 1 NAS via Thunderbolt connected

Yesterday, my iMacPro crashed every couple of minutes. Disconnected external monitors, everything stable. @Apple: This bug is super-annyoing, and needs to be fixed ASAP. It renders an expensive machine useless... userspace watchdog timeout: no successful checkins from com.apple.remoted in 180 seconds ...