Drupal ubercart volume pricing not including attributes

Question

In my Drupal Shop I have some products with different attributes and options. For example the Colour 300ml with option yellow, green and brown. And the Colour 500ml with the option yellow, green and brown.

I also have different pricing volumes. At a quantity of min. 14 the product is 1$ cheeper etc.

My problem is that the cart doesn't count the items together which are from the same product:

So I buy for example Colour 300ml - yellow - 10 pieces. In the cart it tells me: buy 4 more of Colour 300ml for a discount. So I buy additionally 4 of Colour 300ml brown.

But in the cart they are seperate. So now it tells me buy 4 more of Colour 300ml for a discount and buy 10 more of Colour 300ml for a discount. One for each colour.

Does anyone know what to do?

Note: I use Drupal 7.50, and I use the ubercart model and the uc_volume_pricing

Answer 1

I tracked the following issue, and got a respond from the developer:

https://www.drupal.org/node/2907493#comment-12256626

This solved my problem, together with the module uc_volume_pricing_incattr