TBD, (to be discussed), instead of shipping price sometimes happens with auto-calculated shipping and means that your store could not calculate shipping cost for the combination of products placed in to shopping cart.
Order shipping price is marked as TBD for both you and your customer so that you will be able to follow up with the customer to discuss shipping prices after order completion.
Order shipping price of TBD happens on rare occasions, usually when product dimensions or weight is greater than the maximum accepted by the particular shipping carrier.
If you are shipping extra large or extra heavy packages I would advice using FedEx as your shipping carrier as they accept bigger and heavier freight.
Steve - eez.io support