Outlook 2013: Instant Search results disappear

[skylark53]

I am running Outlook 2013 on Windows 7 (SP1).

 

When I use Instant Search on my own mailbox, no problem. But I also have full access to 3 other office mailboxes, all of which I am required to monitor and need to search frequently.

 

When I use Instant Search in one of the other mailboxes, Outlook 2013 appears to delete the results as soon as they are found.

 

In the status bar at bottom, outlook reports that it is 'indexing'. But as it does so, the results disappear from the window. See attached sequential screenshots 1, 2 & 3 (edited for privacy), taken a few seconds apart. In this case Outlook finds 4 results for the search word 'alford' and then immediately 'deletes' them.  It can take 3 or 4 passes actually to read/open an item. AYMI, this is frustrating and time-consuming (not to mention alarming!).

 

There are two other people in the office with -notionally- identical mailbox access but neither reports any difficulty with Instant Search (which they too use frequently).

 

Does anyone have any idea what might be wrong, or what setting needs to be changed? 

 

Thanks!

Edited May 5, 2015 by skylark53