After a few restarts of Outlook and a restart of the computer I was using to test, mine to has started to work again.
I have spend the last 2 days removing all reference to company emails for some of my customer who were seeing an issue with the search. This affect some but not all user at these locations.
Company domains still exist within MS Teams and I am sure this will cause some issue going forward where this is not integrate with AD, so we are scheduling to do this over the next few weeks/months, not ideal because so many people are working from home!
What I fail to understand is why MS would promote the Autodiscover to THEM before looking at companies DNS. Is this that MS believe that we will all end up in the cloud, on their platform, in months/years to come and if we don't take this decision, then they will force us by making changes to their systems, which will stop us working using inhouse system like Exchange.
I accept that they have fixed this problem for now, but as state above this is the second time in the last few months that this has happened, excluding the issue last Wednesday where people report Outlook not working at all after an update. This was fixed very quickly by MS, who withdrew the updates and fixed whatever they broke with the current version of Outlook. Reference here https://techcommunity.microsoft.com/t5/outlook/outlook-365-suddenly-won-t-open/m-p/1528005#M4978
I accept Gabe_Bratton these are not your decisions and thank you for your help.