Using classic Outlook for Windows in business environments
Given everything you have already included as to what has been done so far - have only two questions and one suggestion
#1 - How are you adding the accounts to Outlook? Specifically, is it by just entering the email address / password for the account (using <auto-discover> or are you manually entering the settings for the account? Am going to assume that you are trying to configure the account normally (just entering the email address / password)
#2 - Normally, the first suggestion would be to create a new Outlook profile using the Control Panel Mail app. Is that the way you are creating the new profiles or are you creating these from within the Outlook desktop app?
#3 - Without knowing anything else, if you have been creating the new profiles using the Control Panel Mail app, the only suggestion would be to do an <Online Repair> of Office via
<Settings> --> <Apps> --> <Apps & Features> --> scroll down to your version of Office --> <Modify> --> <Online Repair>
*** an <Online Repair> is an uninstall and reinstall of Office. In very rare cases, the reinstall does not complete. If this happens to you, the solution is to log into the Microsoft Account associated with Office --> click on <Services & Subscriptions> and download / install from there