When villagers are set to follow the player and are teleported to that player when they are far enough, setting them to move freely causes them to disappear.

Do they disappear or do they return to their next POI, e.g. work station?
If you are familiar with an NBT editor, can you search for affected villagers?

Closing as technically intended, as the WanderOrTeleportTask works both ways. Bring them far enough, and they will TP to their next POI if they get another WalkTarget.