Villagers not entering Nether Portals

Villagers are not entering/traveling through Nether Portals.  The portals have been previously used and link to Nether-side equivalent portals.  Villagers will not enter the portals when delivered by boat (hitbox directly interacting with portal tiles upon being forced from boat) and will not travel through portal when walking through.  Villagers are not on cooldown from previously interacting with a portal.