TR-8S doesn’t start in sync with MPC HELP!!

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I’m totally stumped. My TR-8S seems to randomly not start in sync for some patterns, I did a factory reset and it was fine, loaded up the backup and the problem returns. So it must be a config issue. I have matched the sync/midi configuration to the factory reset settings but the problem is still there. At one point it got even worse and was making a fart noise at the start of each pattern. To make it more complicated the same pattern plays either perfectly or with delay depending on which sequence from the mpc starts it, but it’s 100% not the MPC causing the issue. Any thoughts. Could the backup .bin be corrupt? I’m going to have to raise a support case I think. Is it worth falling back to the os before 2.51 as I can live without the mac editor for now.