When you use package manager to move a collection of cloud pages, be aware that it will only move 49 and the rest of the cloud pages will not be picked up.  You are unable to select individual pages so if your collection has more than 49, you are out of luck.  We had to copy each landing page into different collections of less than 49 in order to use package manager.  We also hit a limit when moving assets in content builder.  Cloud pages acts like it packaged all your pages, but doesn't.  When selecting assets for more than 50, it simply crashes.  You have to manually select 50 individual assets at a time, package and repeat.  SF is aware and are working on the bugs.