FAWE - FastAsyncWorldEdit completely stops when it hits a Quark Quartz Wall. Video - https://www.youtube.com/watch?v=R_yyRFJ1kfw&feature=youtu.be

I was copy-pasting my house over and over, deleting specific modded blocks until I deleted the quartz walls off of my house. Then FAWE could easily copy-paste my house without any errors.

The errors produced in console goes as follows - https://pastebin.com/CNRrcXrc

This must be a quark-related problem, and I hope you fix it.

"Well, it is modded Minecraft which could definitely cause conflicts with the way FAWE handles it's caching of ID's
Though it should be supported, these things happen when it comes to mods."
-FAWE Dev

This is not a quark issue.