I would have to test out the solutions to see if they work. It could explain it in both relm circumstances I had. In my first relm I did interact and they despawned and the second relm I did not, thank you.
Still in Minecraft 1.9 pre-release 3
Most of the time you don't see the glitch. But sometimes you see it very clearly.
Sort of fixed in Minecraft 1.9 pre-release 2
Still in 16w05b.
I guess I just have the workstation bug to worry about then.