I'm having this exact issue. There are several T-80 tanks on the Lebanon map that have this bug. It may be with all tanks, it has happened to me several times all over the map. But the three sitting in Damascus Intl. Airport always have this issue. What happens is the hellfire will track to the target, then at the last second before impact it will snap off to the side and hit next to the tank. This happens using a Longbow/Radar type of hellfire where the target is locked in LOBL or LOAL mode. Romeo/Laser hellfires seem to target correctly.

EDIT: I just played the Thailand map and the same thing is happening with some T80U tanks.

This was happening in 1.16.1 and is still happening in 1.16.2