Outlook (365) Need Password - Issue

Hello all!

I'm hoping my experience in this may help someone with something they may not have thought of...
July 10 2023 was the start of my hell period - started with one user being challenged for MS Password out of the blue - then one by one most of the organization started getting the popups almost every day or every other day. The sad part was that a small portion of our users started getting the dreaded "Outlook Loop" following by "Need Password" as the condition message (causing all Microsoft Products to fail by the way - including Teams and OneDrive.)
Opened about 4 trouble tickets with Microsoft during this period, with little or no solutions until the last agent, who was in contact with more senior support staff, asked what AV solution our organization uses. This location uses Trend Worry Free AV (Client/Server), and they suggested I "try it without Antivirus" - I initially balked as NOTHING changed in that area and couldn't have been caused by that but as a IT Tech myself I knew it was good practice to rule it out. We removed our corporate AV solution on 1 test machine with severe restrictions on usage and wouldn't you know it, all the problems went away! I was shocked - again NOTHING changed in our AV - no patches, no updates apart from the pattern files. (There were also no scheduled Windows update either - however the Microsoft Office Product offering is set to automatically install updates) The agent added that they have documented reports with customers with our same setup and the issue was the Antivirus. So Pass the buck time... I opened a case with the AV provider and in short order they had reports of this same issue as far back as May 2023 - they stressed that the problem is not just with their AV product but that it has been reported WITHOUT ANY aftermarket AV Solution! (implying Microsoft) Anyway for ANYONE that is curious what OUR solution was here is a synopsis of the Changes to OUR ANTIVIRUS SOFTWARE - Trend Micro:

I. Under Real-Time Scan / Scheduled Scan / Manual Scan> click +Add
Under directories in the Folders tab:
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C:\Users\*\AppData\Local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy*
C:\Windows\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy*
C:\Windows\SystemApps\Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy
C:\Users\*\AppData\Local\Packages\Microsoft.Windows.ContentDeliveryManager_cw5n1h2txyewy
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Antivirus/Antispyware, under files tab:
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C:\Windows\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Microsoft.AAD.BrokerPlugin.exe

II. Under the Behavior Monitoring Approved List:
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C:\Windows\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Microsoft.AAD.BrokerPlugin.exe
C:\Users\*\AppData\Local\Packages\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy*
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III. For Trusted Program List:
Trusted Program List > Add program full path
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C:\Windows\SystemApps\Microsoft.AAD.BrokerPlugin_cw5n1h2txyewy\Microsoft.AAD.BrokerPlugin.exe
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I can imagine the headaches out there after reading all your reports -
Thought I'd add this avenue in case it helps someone out there.

Good Luck!