Have patched Windows 8 mail app to the latest patch. It now appears that I am unable to select a group/batch of emails to move to a folder when I am in search/filter mode, this has to be done rather labouriously one by one. Why cant I do ctl+click or select all in this mode to select multiple emails to move?

Would suggest you to uninstall Mail app then reinstall and check how it works.
Note: Uninstalling and reinstalling Mail app includes, People, Calendar and Messaging in it.
Follow the steps:
a. Right click on the “Mail” App and select “Uninstall” option.
b. Once the “Mail” application is un-installed, press “Windows key + W”.
c. Select “Store” option from the list.
d. Type “Mail” without quotes in the search box.
e. You will find “Mail” application listed in the left panel.
f. Select “Mail” application and select “Install” option.
g. Once the “Mail” application is installed then check if this fixes the issue.