I would make sure to include the dcm2niix version number in your report, and ensure it is the latest stable version (v1.0.20210317). It sounds like everything has processed correctly. I would check the slice times in the JSON files. I wonder if this data was acquired with Siemens MoCo, which can do odd things to slice times (my own preference is to acquire data without motion correction, and model motion effects in your subsequent analyses).