Microsoft Office from 2013 onwards addin resilency setting may disable customised addins if those addins are perceived as slow to load when opening Office applications.

Please see this article for further information – https://docs.microsoft.com/en-us/office/vba/outlook/Concepts/Getting-Started/support-for-keeping-add-ins-enabled

If you experience issues with either the Word or Outlook DocAssist addins becoming disabled, (either the DocAssist addin icon is not visible or not responding) we recommend you edit the following registry settings for all DocAssist users.

[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\Resiliency\AddinList]
"DocAssist"="1"

[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Word\Resiliency\AddinList]
"DocAssist"="1"