Hi Glenn,
Thanks for the reply - I just checked and I am running the following version (appears to be latest):
Version 1709 (OS Build 16299.98)
In this version when I click on "Advanced Scans" and then "Run Windows Defender Offline Scan" - I receive the pop up to confirm I want to run the scan and then nothing happens - I've left my laptop for over an hour and nothing starts or reboots etc.
There is no error message or any indication that anything is happening. the screen shot below shows all I see after trying to run the scan. I can then press cancel or just close the window with the X.
I was planning on getting a USB key and trying to run WDO via this - however can see you have indicated that this functionality might have been removed.
Alternatively I was planning on downloading the following Microsoft Safety Scanner and running it later this evening:
https://www.microsoft.com/en-us/wdsi/products/scanner
I was not sure if WDO had been disabled by whatever trojan or PUP had been detected earlier and as such was planning on refreshing my PC - and seeing if WDO works thereafter (after running all relevant windows updates)