When attacking and destroying a Town Center with a lot of Anubites one of them got stuck on the settlement.
Note: There have been other instances of other units getting stuck in things like a gold mine for example. It seems units get pushed into things and then get stuck is the cause.
can confirm, this hapened several times to me as well. One of my centaurs got stuck into rocks in the underworld mission and one of my villagers got stuck between rocks and gold mine in one of the greek missions.