Input assignment is handled on the Mix Preview page as you begin to run mixes, the second page listing your carrier and product(s) and their intended amounts. Select the product you need to assign an input to -if one is already assigned it will show that as you view the list, no need to select the product to confirm that it's assigned. 

You may leave the product UNASSIGNED if you DO NOT want the Mixmate to run that product and you are manually adding that product to the mix.

Select the Mixmate you are going to use to make the Mix

Select the work order you are mixing

Press the blue '>' when you are satisfied with the information on this page

To select the Mixmate input for the product, press on the product line to get the Mixmate Input selection Modal.

Finally once all the data on this step is satisfactory, press the blue '>' to start the Mix