When using update_field() where a value has not been previously saved you need to use the field key and not the field name. get_field_object() using the field name where a value has not been previously saved will also return no value.
When you are working with fields, any field type, where a value may not already exist you should always use the field key rather than the field name. This is explained on this page https://www.advancedcustomfields.com/resources/update_field/
