Observers can send a redstone signal through transparent blocks and certain tile entities, as shown in the screenshots, yet solid blocks and other tile entities do not transmit a signal.
MC-109128
Observers "power" transparent blocks
Resolved
Awaiting Response
0
Landon D.
(Unassigned)
Unconfirmed
Minecraft 16w42a
Retrieved
Powering blocks broke in the current snapshot, check the next (upcomming) one to see if anything changed