PS 1.6.1.11 - Carrier not appearing on FO on certain products

[SirachMatthews]

I am running PS 1.6.1.11 with the Canada Post Module and the Shipping Costs per Zipcode, Zone, Country, State, City Module.  When I first set these two modules up, everything seemed to be working fine, but recently I have noticed a lot of abandoned carts.  It seems when customers are checking out, they are receiving a warning that there are no carriers that deliver to the address provided.  This just simply is not the case.  Using the Shipping Costs per Zipcode, Zone, Country, State, City Module, I have a Zone setup for local delivery based on City name, one for Market Pickup based on Postal Code ranges, One for Canada and one for the USA.  I have set my local delivery to be available only to my local delivery Zone, and my Market Pickup carrier to be available only to my Market Pickup and local delivery Zones.  Likewise, I have setup the Canada Post Expidited Parcel to be available to the Canada Zone and Expidited Parcel USA to be available only to the USA Zone.

I have tried selecting carriers at the product level which yields the "No Carriers deliver to your address" error.  When I remove all carriers from the product level, only carriers from the UPS Shipping Module become available at checkout.

When I added a new product the other day, the Canada Post carriers worked and were available at checkout.  When comparing differences between the new product and an existing product, it seemed like the package dimensions and weight were missing from the existing product.  After adding that important information, the result was unchanged.  The existing product still produced the error, while the new product continued to function properly.

I have run SQL queries to try to compare the records for these two products without seeing anything different except the details which ought to be different.

SELECT * FROM `ps_product` WHERE `id_product` IN (5,31);

And

SELECT * FROM `ps_product_shop` WHERE `id_product` IN (5,31);

I am at a loss, and almost ready to try adding duplicate products to see if that resolves the issue.  I really do not want to recreate my entire catalogue if I can avoid it.

--UPDATE--

Well, the issue gets weirder.  I managed to resolve this issue on all products, save one.  Somehow the package dimensions and weights reset to zero on many products.  That was an easy enough fix.  However, one product in particular was not cooperating at all, even when trying to add it as a new product, or duplicating the original.  In order to get this product to work properly with shipping carriers, I had to duplicate a different product and edit all the information to match that of the original product.

Edited March 11, 2019 by SirachMatthews (see edit history)