We have encountered problems with Dynamics 2013 on-premises Outlook plugin after the Office 365 monthly update 1906 was released in June:

When we click the Set Regarding button on any new e-mail message, only a blank dialog window appears and Outlook hangs. However, the dialog still opens normally in old messages linked to CRM prior to the 1906 update. Additionally, we are unable to access any CRM plugin settings from the File->CRM menu. A blank dialog window will appear there also.

Following errors appear in the trace log:

[2019-07-16 13:51:06.901] Process:OUTLOOK |Thread:15224 |Category: Unmanaged.Platform |User: PlatformUser |Level: Error | IObjectSafetySiteLockImpl<class CUIUtil,1>::GetInterfaceSafetyOptions File: c:\bt\102359\src\core\application\outlook\addin\..\include\sitelock.h Line: 796
>hr = 0x80004002

[2019-07-16 13:51:06.901] Process:OUTLOOK |Thread:15224 |Category: Unmanaged.Platform |User: PlatformUser |Level: Error | IObjectSafetySiteLockImpl<class CUIUtil,1>::SetInterfaceSafetyOptions File: c:\bt\102359\src\core\application\outlook\addin\..\include\sitelock.h Line: 833
>hr = 0x80004002

The problem seems to affect Windows 10 computers only. In Windows 7 computers the CRM plugin runs fine even after the 1906 Office update. In Windows 7 implementations we are running the 32-bit version of the plugin and in Windows 10 implementations the 64-bit version of the plugin.

Any suggestions?