Hi Ross
Thanks for your reply.
In the meanwhile, I found the solution.
I deactivated all my plugins and I got my command tabs back.
So, I reactivated the plugins one by one, and I found the guilty one : it was Polylang for Woocommerce.
I sent an email to them and I had an answer.
I had to set the admin language filter in the top bar on “Show all languages” and then it worked perfectly.
Maybe this could help other people !
Thanks for being here Ross !
Christophe