Thank you Alexandre. Unfortunately, the log you provided us is not related to this issue.

It’s best if we take a quick look at this…

Could you create a new website user for us please? If possible with administrator capabilities so we can make a quick check of your settings.
You can post the user name and password in your next reply and mark it as private to keep this between us.

Also, are we free to deactivate plugins for our tests? In this case, I invite you to make a backup before we investigate your website further in order to make sure you don’t loose any data if something goes wrong.

Thank you.