Will look through those / have been looking through those. Yeah I posted quickly as a shot in the dark, I strongly suspect user error, and thought maybe OP had made a similar user error. The thing is I used to have it working great, just rebooted my scope and now have not been able to get it working again. Double checked all settings, tried literally every combination or thing I could think of and I still for some reason have my scope hat believes 8 bits are being coded on 2 clock cycles. It seems to be taking into account both rising edges and falling edges, though it's not super consistent in that behaviour (sometimes +1 bit or -1 bit relative to clock cycle count).
'l'll post screenshots when I am home, I'd be hardly surprised if it is indeed user error, but at the same time, the options are pretty limited for the settings, I've replicated the same settings that got it working at first, and then tried everything else I could think of and still have this odd behaviour.