When you are creating a Material on the Library, you will be shown the option to mark your material as 'Intentionally Quiet.' If your ad is deliberately quiet and under the normal EBU R128 Target Level (for example, your client might be a meditative app or your actors might be whispering or the ad might be completely silent for dramatic effect), then you should turn this slider on.
This will affect the Quality Checks your Material goes through. If you click on this toggle (turning it purple), the system will not go through the audio QC.
A key component of the new HD Standard is the introduction of an exceptions process for intentionally quiet content. This will enable producers to deliver creatively quiet content that does not meet the normal EBU R128 Target Level, a key aspect of the R128 recommendation for short-form content. It also includes requirements for Short-Term Loudness, which further aligns with the EBU R128 recommendation. So if your ad is not intentionally quiet, then selecting it could mean it is inaudible on TV and it will not be checked.