Hi @gregattack
Are you using the update_field on a $post which already has a value? Or are you saving this repeater value to a new $post?
If you are saving to a new post, then ACF will not know that it is a repeater field! To bypass this issue, please first read the update_field docs and pay attention to the $field_key parameter.
If you use the field_key, instead of the field_name, the repeater field will be detected and the data will be saved correctly.
Hope that helps.
Thanks
E