Unable to Assign TaskTemplates to Asset/Shot/Episodes that contain Assignees

Bug occureed recently, previously was able to run the command

session.update('Asset',xxx,{"task_template": {"type":"TaskTemplate","id":xxx}})  

but now this will error if the task template includes tasks that have assignees, with the following result….

shotgun_api3.shotgun.Fault: API update() CRUD ERROR #900: Task Template failed: [ 5 - Update failed for [Task.task_assignees]: undefined method ‘oxygen_user_id’ for an instance of ApiUser]