Evri - Buy Shipping In Bulk

We have recently joined Evri alongside our usual couriers Royal Mail and DPD.

We now use Evri for a specific item as it keeps the costs down due to size of the item. However we are selling between 40-60 of these items a day, and we can't seem to buy any of the orders in buy bulk? Meaning that we have to go into each individual order details and buy shipping this way, which is taking forever.

It now sometimes chooses Evri as the option for a few other prime items, which we are able to buy in bulk buy.

Would there be a reason why this specific item cannot be bought inside bulk buy? The measurements are weights are all correct.

Its taking me around 20-25 minutes every morning just to get these labels one by one.