User blog comment:Scooter8pie/Transparency Bug/@comment-4583259-20111108051212

It appears that the transparent bug affects vertical strips of blocks that are 1 block wide and the entire height of the world.

Find a transparent surface using Scooter8pie's "put a bunch of lights down" method. Now drill straight down as far as you want (I went about 50 blocks) to make a shaft with a transparent side. As soon as you "break the surface" by drilling through the transparent side, the entire vertical shaft (all 50 blocks) becomes normal (not transparent). But you can mine just one block to either side (left or right) and you'll have new transparent blocks. You can also extend these new shafts up as far as you want, and they'll be transparent all the way up/down.

If you save and exit, then re-enter the saved moon, the transparent blocks become solid -- but you can (again) mine to either side to expose new transparent blocks.