Hi Bruce Johnson1,
Welcome to Apple Support Communities. We understand that, "Screen Off" displays 0 minutes for the activity usage of your battery. We'll be happy to help.
Has the screen remained locked with nothing displayed on the screen, while listening to music or podcast? Also, have you waited between 24 to 48 hours, since the update to iPadOS 14.2 for this specific behavior? If not, we suggest to give it 24 to 48 hours and see if, "Screen Off" continues to display the battery usage at 0 minutes. Please keep in mind, background activity needs to be in use, such as listening to music or podcast for "Screen Off" to display any sort of usage in Settings > Battery.
We look forward to hearing back from you with an update.
Best regards.