When the number of posts for a specific platform hits 5, we group them into a single location. The reason for this is to improve performance and usability. If changes were made at a page level, then platform editing will be restricted. This is to avoid the lower level changes getting overridden.
This situation occurs when one of the franchises has already customised the post for their specific location. What that means is that you have already approved the post and the individual franchises have had a chance to edit the post and make changes.
There is no way to bypass this behaviour other than to email the franchises and ask them to roll back their changes to unlock editing on this platform.
Why is Customise Restricted
Unfortunately, due to the complexity of running the data in so many locations, it becomes very hard to manage the state of all the locations.
The simplest way around this problem is to ensure that content is complete and won't change prior to approving it. In doing that, the franchises cannot overwrite your changes.