If you are enrolled in Targeted Audience Solution (TAS) and not hearing a TAS ad playing when you listen to your podcast, fear not. Your TAS and Ad Ops settings are more than likely correct (reference here for more information on Ad Insertion Points). TAS does not have a 100% fill rate and varies by series and audience. You're able to determine your fill rate utilizing the monthly TAS impression report that accompanies your monthly statement.
Should you have additional questions regarding your series and TAS feel free to reach out to firstname.lastname@example.org for support!