Tokens missing in Webform Email Settings (and thus not populated in Emails received) (after upgrading)
Thank you to both of you (Karin and Pete) for your suggestions : I have solved the problem.
I have disabled Token and Entity Tokens Modules (and requested associated Modules)
... then reactivated :
The probem comes from the Advanced User Management Module : when it is enabled, most of the tokens cannot be browsed (among which the default proposed ones in the mail content).
I will post this answer on the Drupal StackExchange.