Hi @Pierre Auger ,
Welcome to our forum!
From you description, seems that it is related to the corrupted old profile, so we suggest you deleted the old profile, then create a new profile from control panel:
Go to Control panel > Mail > Show Profiles, then deleted the old profile and create a new profile, re-add the account.
Besides, in order to avoid the influence of the old version, it is recommended you check the version and upgrade it to the latest:
In Outlook, go to click File > Office Account > Update Options > Update Now
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