Update: Still unable to launch Chrome RDP for GCP within GCE, however, as of today, I am now able to manually enter the IP into the regular FusionLabs app for Chrome RDP (not the GCP version) and it opens my VM. Of course, I launched the Chrome RDP app manually from a browser tab (not from within GCE). In the past, as recently as yesterday, the Chrome RDP app did not open my VM, only the GCP version would work. But at least now, I can access my VM, I don't really care that I have to launch an app manually to do it.