Hello,
I have exactly the same problem.
A ROG G702VMK-GC375T to which I connected for the first time this week an ASUS VG248E monitor.
Works very well in HDMI, but not to the max (144Hz).
Using a Mini-DP to DisplayPort cable, the monitor says "No signal on DisplayPort".
Why? And what can I do to make it work?
Thank you