ERROR: One or more items in this shipment cannot be sent. Reconfirm shipment quantities on step 1 to view details on the error in order to activate the confirm button.

There are ASINs in the batch which are added more than allowable quantity in your account. Please check the LTSF(Long Term Storage fees) removal restrictions in your Amazon account in Seller Central and accordingly update the item quantity in the batch and progress the batch from Step 1 again.