Just something I noticed about something I've been working with. What I was making was an unfolding rotator-based wall. There's about 4 entities chain-docked. Over long periods of time, the "later" entities in the chain will lose collision, as well as my ability to select or interact with its blocks. Pain in the ass when trying to logic. I've also got a previous version of the entity that hasn't disappeared yet after I used /destroy_entity on it. It's also non-collidable.
Completely...
No Collision (Rail) (Over-Time)
Completely...
No Collision (Rail) (Over-Time)