Hi LBH, I appreciate the replies, thanks. This problem has been reported before (I Googled it) but I could see no solution.
Yes it worked fine previously. I have not used Live for some time so cannot be sure when/why this started.
Yes I am using Win 10 64 bit with 64bit Live 10.1 and 64 bit plugins.
I have raised a ticket, I will try to post any solution.
Cheers.