Firstly, there are none of my own code customisations, purely a custom theme based upon Twenty Twelve.
With ONLY the following plugins active:
– Advanced Custom Fields Pro
– The Events Calendar
– The Events Calendar Pro
– Ultimate Maintenance Mode
With Twenty Sixteen active – search feature works.
Switch back to custom Hollowells theme – search feature stops working.
Further to this, with Twenty Sixteen and ALL installed plugins active, the search feature works.
Must be somewhere within custom theme I guess.
Jon