External 4k display frequently blacks out after sleep

Every time my MacBook Pro has gone to sleep (both while on power adapter and battery), my external 4k monitor (ASUS MX27UC, hooked up via USB-C) starts turning black for 2 seconds and then switches on again every few seconds. This happens frequently but aperiodically it seems. This is being fixed with a reboot (until the laptop goes to sleep again).

I used a Macbook Pro 13" (2017 with Touchbar) before in the exact same setup and that didn't have the problem. I played a bit with the energy saver settings—without success.

Is this a known issue? Are there fixes for this? Where can I access (potentially graphics drivers related) system logs?

Thanks, Sven