Why is there a discrepancy between different level's compliancy scores?

For example, you observe that the overall compliance score is low (0% here) whereas the compliance score by guideline is not always 0%. 

Please note that the overall compliance score represents the number of invalid entities (campaigns, adsets, line items, etc.) compared to the total number of entities:

The reason for this discrepancy is the following:

If a campaign/entity has at least 1 guideline invalid it will be flagged as invalid in the overall compliance. If you are applying 10 guidelines at the insertion order level, and 1 guideline is not compliant on a single insertion order, the insertion order is considered as invalid in the overall compliance (despite the other guidelines being compliant).

If any doubt persists, you can reach out to support@grasp.gg.