Configuring preferences and options in Outlook.com
according to this question https://answers.microsoft.com/en-us/outlook_com/forum/all/microsoft-365-personal-subscription-premium-get-a/8b8339b1-ef9c-442b-bb34-81003def784b, the bug has been fixed.
We'll see..
But the fact that Microsoft treats paid users of non-business plans so bad (misleading support, no communication via any official channel, etc), make me wonder whether I should trust their reliability