We recently had a severe issue with incomplete and then totally broken synchronization between one of our BigCommerce stores and Shipstation. The main troubleshooting strategy of the support team was to ask us to perform the “edit connection” step, repeatedly, until it worked. In total I think we did this about 12 times before it was successful, over 3 support calls spanning 5-6 hours.
For those of you who haven’t done this process, it is very sensitive to what browser you do it from and having no cache history of other store/SS logins that can corrupt the linking process, which is simply logging into the desired store and SS account while installing the app in BC. This is a really WEAK way to connect two platforms, and I could not believe how many variations I saw in the process, it would not unfold the same way every time.
ACTION - what I suggest is to use something far more straightforward and reliable to connect a store to a SS account. Perhaps after installing the SS app in the store, the SS app could generate a code that is entered in the store configuration settings in SS. Would that not be an infinitely easier and more reliable way of connecting a store to a SS account?