I only have MS defender for win 7. I disabled that and tried.. no change.. same issue.
Then I did the following.
I completely uninstalled CYVR. and reinstalled it only for v3 (not for v4) and had the same error. And made sure the Addon folder for v4 did not exist.
I then copied (from my backup HD the CYVR folder (this was the v3 version was fully functional one time before the new file structure change. into a separate folder of my own and added it manually to the scenery.cfg.
within v4, I notice in addon manager that CYVR is installed and active. And the CYVR is visible...all buildings etc, but the ground texture is completely black when I am close to the airport, and look ok when I am away like 20 miles out. Thought this workaround would work..but nope., I am out of ideas.
I own every single FSDT airport now and they all install, except this snarly one. And others have reported the issue.. My take would be , a new build file.