When you first set up a Seller SKU in Seller Central, it is of paramount importance to create a unique SKU name for your listing. Otherwise, Amazon will use your product title as your SKU name. If your product title contains certain specific abnormal symbols, it will cause BQool to fail to update your product information.
Please also note that the system cannot differentiate between upper and lower case. With this idea in mind, please don't use the upper and lower case in the SKU name to differentiate two different listings. From the system perspective, they are still the same SKU, which will result in one of the Qty data can't be reflected accordingly.