Cannot Open Office 2019 OutLook365

JamesMNTexas 

Since you were able to reproduce the issue in Outlook safe mode (outlook /safe) that means no 3rd party services are contributing with the concern.

It seems like your Outlook (OLK) instance is stuck in authentication with the Exchange Online (EXOL).

IF it is stuck in loading profiles, I'd suggest below configuration then re-open again OLK.

Office apps should be enable for modern auth:

Go to: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity

Add DWORD:

"EnableADAL"= 1

OLK should be force in using modern auth:

Recommend that users force Outlook to use Modern Authentication. To do that, set the DWORD value of the following registry key to 1. 
HKEY_CURRENT_USER\Software\Microsoft\Exchange\AlwaysUseMSOAuthForAutoDiscover

From <https://docs.microsoft.com/en-us/exchange/troubleshoot/modern-authentication/modern-authentication-configuration>

EXOL should be using modern auth:

1. To enable modern authentication, go to the admin center at https://admin.microsoft.com.
2. Choose Settings > Services & add-ins and then choose Modern authentication from the list.
3. Check the Enable modern authentication box in the Modern authentication panel.

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/enable-or-disable-modern-authentication-in-exchange-online

Polite as usual,

BFN

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