File a support Case on Google Admin
Sometimes the issue is at Google's level.
In this case here is how you can file a support ticket :
1 - Go to : https://cloud.google.com/support-hub/
2 - Click on "File a support case".
3 - Click on "Cases: Create a case"
If the issue is related to an account not seen by us when updating the signature here is a text sample :
We are using Google's API to update our email signatures.
We can't update the signature for email xxx@sss.com
Any questions ?
You can describe your problem orally in a few seconds leaving a message on the
+33 1 83 64 02 13
You would rather write it down? We are happy to help in response to your email at