Thanks for the video, we've added it to our bug database as additional information.
Regarding the glass blocks in the video, they appear when you have a prefab.
Please, add to Worldbuilder Prefab space few maximal builder skills. It's more difficult to make prefab with lowest stats.
Are you referring to the Testing version in this case?
Yes, I do. It's hard task to make something in Testing version with default (lower) stats - quickness and work distance. And how I understood here isn't some way to have different skills in World Builder.
Thanks for the confirmation, we had a look and agree that creating prefabs is a lot slower than before, so we will take a look at it.