Can you try disconnecting the current connection and setting it up afresh? To do this, go to the hidden debug page: example.com/wp-admin/admin.php?page=connection-test-admin-page (replace example.com with your domain name)
1) Under Merchant Center, click MC Disconnect
2) Under Google Account, click Disconnect Google Account
Then go to Marketing > Google Listings & Ads and set up again.
If the issue persists, please create a support thread and share your site’s system status report so we can help further.