Defenses disappearing prematurely

[Nothing]

I've noticed while playing this morning that enemy defenses would sometimes disappear shortly after I conquered them. These weren't old defenses waiting to crumble, they were active ones that I'd just conquered seconds earlier.

It happened at least six times that I noticed (out of at least 100 attacks on enemy defenses), appeared to be completely random, and occurred with both walls and towers.

[Sphinx]

Its a 10% chance.

[Nothing]

Huh, I didn't know about that.... that'll be good to know when going after orbs.