I am having the same problem - i have loads of items that have been made inactive for some reason and when i try to make them active i get the same message Product state not changed: Magic Box items which are not limited quantity can not be listed.
I do not understand why this is happening as i only have 50 on hand. https://marketplace.secondlife.com/p/PB-Advertising-Vendor-xstreetsl/484972?preview=true
Please help