I have had this issue before. New cable, new watch, no problem, but after two months of use of the new cable, it intermittently refuses to connect to my Mac. The screen lights up, it charges, but it does not show the file contents.
I have tried everything, jiggling the cable, re-attaching, restarting, and then randomly, the SBP file shows up at some point. I cannot pinpoint what makes it read the file sometimes and sometimes not.
I have sent mail to the shop support here but have had no luck with any responses. The last mail actually bounced. Hoping for some experience out there with the issue and how to solve it?