Accidental war -- peace declared, ROW granted, units still locked together

Does anyone have any experience with this scenario?

Accidental war, units got too close, combat started, players declared peace, granted reciprocal rights of way, one unit is still attacking the other but no damage is inflicted, units appear to be locked together as if in combat and apparently cannot move. The "attacking" unit is no longer counting down to the hourly battle damage update, but still displays the battle shield icon above the unit icon.

Any suggestions from other players would be appreciated, and I would be grateful if any knowledgeable game operator would take a look at this and see what can be done. Game 1702073, see Hilo province (Hawaii).

UPDATE: The defending unit was able to depart after several hours; the attacking unit remains frozen in place.