Yeah, I’ve noticed that AC has very good survivability as well.
I don’t think surviving badly placed TnT is something extremely unusual tho. It has only 35mm penetration. So it is probably not bugged, only has strong armor on the top.
A.C.I is the allied version of kv1, the only reliable way to kill it up close is planting explosives on the turret roof, the only place infantry explosives can pen.