Dooh just twigged what I was missing!
Instead of trying to select a custom panel at the bottom of the list I should have instead selected the "CW Custom Panel" and then select whichever panel from those listed from your loaded library
Happy days
AC versions 3.41 to 25 (UKI Full 5005).
Using AC25 5005 UKI FULL
Mac OSX 10.15.7 (19G2021) Mac Pro-2013 32gbRam AMD FirePro D500 3072 MB graphics