Hi Jason. Thanks for your support.
There is a cookie already listed in the WA Cookie Variable list called "Form Cookie(FORMAboutYou)". I've tried deleting that, and then recreating it, but that doesn't resolve the matter. Nor does, as you suggested, typing in the name of the cookie binding. The Cookie name drop down remains empty.
So...I've deleted the sites _notes folder. No change there either.
Any other thoughts? Thanks again for you help.
AH! Maybe deleting the _notes folder has resolved the issue with it not taking the typed value in the WA Cooke Variable list. It appears to be appearing in the Cookie name drop-down menu now.