update_field, acf_update_value, & acf_update_metadata seems to always return false

In my case, update_field always returns false when updating a user_ field. It seems acf_update_value eventually calls acf_update_metadata and it seems to always be false because update_metadata seems to always be false because the eventual $result = $wpdb->update( $table, $data, $where ); always fails, even though the meta appears updated.

When I dump these out:

            [$result] => 0
            [$table] => wp_usermeta
            [$data] => Array
                (
                    [meta_value] => 3
                )

            [$where] => Array
                (
                    [user_id] => 77
                    [meta_key] => author_bios
                )

It looks like the update here really is just updating the ID of the field? I'm not sure, but this is just updating it to 3 again which really doesn't update the table since it's already set to 3.

So the problem here is I can't rely on update_field to tell me if the DB was actually modified or not for the actual field value I'm trying to change.

Start by tracing the reported path from update_field through acf_update_value and acf_update_metadata into update_metadata and $wpdb->update. Reproduce the user_ field update against wp_usermeta where meta_value is already 3, then verify the intended return value when the stored value remains unchanged.