We have this peculiar problem with Enterprise Vault Search in our entire environment. The Submit Search button (blue with search icon) is not clickable from within Outlook but works when EVS is called from IE or Chrome.
The behaviour is the same in Outlook 2013 and Outlook 2016 and exists only when EVS is called from within Outlook. Am trying to identify if this functionality is broken with any new Office patch or update or a setting within Outlook to block any scripts in web pages called using add-ins.
Outlook 2016 16.0.4738.1000 64 bit
Enterprise Vault Outlook Add-In 188.8.131.525
Thank you, Gertjan. My current issue is the Submit Search button inside the EVS page (when loaded in Outlook) is not clickable. We can hit 'Enter' to run a search but clicking the Submit Search button does nothing.
The technical article you posted is for the issue where the 'Search Vaults' button itself is not clickable and it was indeed resolved in the 12.3 Outlook add-in.
It looks like this known issue:
We're aiming to have a fix out for it in 12.4.1, and of course all the usual caveats apply (release vehicle subject to change, not a guarantee, etc.).