Hey @Daniel_Moseley and @DavidT
Good news - our team identified and fixed the root cause. There was an issue in how bulk mutation jobs were processing lines when operations were interrupted and retried, which caused some lines to get skipped in the response file.
Can you confirm whether you’re still seeing missing lines in your bulk operations since then? If you run a new bulk operation now, you should see all lines present in the response.
Thanks for the detailed reproduction info and bulk operation IDs - that really helped the team track this down quickly!