I have imported 270 subscribers to our Associate Members Plan which is Free.
I set Upgrade Option from Associate to Full Membership - Paid.
I have Joomla Groups also named Associate & Full. This so I can give discounts in your xtn Event Manager.
I set Joomla Group Settings to move user from Associate Group to Full Member Group.
I then in front-end log in as user barryP and view Membership Profile. Choose to Upgrade to Full. Pay.
All looks good. Membership Pro shows I am now the only Full Member.
BUT I am STILL in Joomla Group Associate !
I have created a superuser login for you but will not post it here.