I haven't had it happen yet in 1.13 pre3. I had it happen in pre2.
If it happens again I'll come report it immediately. Hopefully it's resolved unintentionally.
(Is there a reply function here?)
That's good to hear! Something I started doing was taking screenshots of the stuff that's in them, in case it happens.
Darn! So it still happens, huh. I did know about other shulker boxes getting the same glitch if you place more, I put this already in the main post.
Once you break all the faulty shulker boxes they work again normally until it happens again.
When you say it happens in certain locations, have you gotten the glitch to happen twice in the same area? As in, one shulker box not working then disappearing, then it works again, and then it's bad again?