You would need to update your annotation files to ensure the index values for all annotations match the classes.
Or, alternatively, merge the coco128 dataset with your custom dataset on Roboflow, and export that way. This will solve the issue of the indexes not showing up when validating your model. However, Roboflow makes the index names alphabetical, so they won’t be in the exact same order as coco128, but they will at least show the results for all classes in the dataset.
