This is what exactly I did on a superflat world.
/player gnembon spawn
/player gnembon look down
/player gnembon jump continuous
Drop a glass block to him
/player gnembon place continuous
/player gnembon place once

Then the game crashed, saying something about entity ticking (I can't remember exactly).

what actions. Please specify commands that you have run and situation it was used in.

can you send the stack trace that pops out?

ok - replicated myself

should be fixed in the next update.