Invalid item for MSKU ZM-OYTH-388D with reason ITEM_EXCLUDED_FROM_COMMINGLING_FOR_EXISTING_MAP. - InvalidRequestException
What this means is that this item cannot commingle with any other item within Amazon's storage; as such it must be labeled.
You can try changing it at the product level here in SellerChamp to include Amazon labels, but if it's still not going into the shipment, you'll need to go into your Amazon Seller Central and look for this ASIN you've created and see if there's an option for you to select to agree to label this item.
If that fails, then you'll need to get with Amazon support directly to figure out what needs to be done about this item.
There's nothing else we can do on our end, since the error is coming from Amazon and we cannot get them to remove it at the product level on our end; so it must be done on their end before it can go into a shipment.