When a dropped stained glass block is in front of a sign or water, the sign or water vanishes. Doesn't appear to happen when the block is held or placed, only when it is a dropped item. Works with stained panes as well.
Possibly related to MC-36329?
MC-51521
Signs and Water Invisible behind Stained Glass
Resolved
Duplicate
0
Stefan Barry Matthews
(Unassigned)
Unconfirmed
Minecraft 14w11b
Retrieved
I think it's related to this? MC-9553
But for the sake of it: The bug can be done also with dropped slime blocks and you can also see through slime blocks placed in the world with the said bug.