AdSense-Connection lost
In January 2021, AdSense is going to change how sites connect to their account. Advanced Ads 1.23.0 contains the change already. However, some users lose the connection to the account after the update so they cannot place new ads or load the ad stats. Ads are and will still deliver properly.
Please go to Advanced Ads > Settings > AdSense, then disconnect and re-connect your account. If you experience further issues then please clear your browser cache.