Buttons and levers cannot be placed on top of filled end portal frames

As can be seen through the screenshots, the eye of ender in the frame has more than enough space to support these blocks. However, they cannot be placed on them without using setblock (which I used for the images). Other blocks such as sea pickles, lanterns and torches can correctly be placed on top.

May be considered WAI, but felt this was worth reporting anyway given the changes to transparent blocks in recent snapshots.