MacBook Pro: 2017 Unable to connect to Dell U2713HM with USB-C to DisplayPort cable
Upgrade to High Sierra (Version 10.13, build 17A405) allows the monitor to display again.  

The picture quality is blurry. It is as if I am using the HDMI input.

It turns out there was issue with the Alogic cable.

At the end I purchased a new set of cables (Konix) and the problem is resolved.