Group rename feature does not update group's page restrictions
Problem
If you rename a group, space permissions are updated to reflect the new group name, but page restrictions (different to permissions) are not updated. The page restrictions will remain in place despite the old group no longer existing, which could potentially cause members of the renamed group to be locked out of pages.
Solution
This problem has been resolved as part of https://thepluginpeople.atlassian.net/browse/CSUM-65. Please upgrade to version 3.0.18 or newer as page restrictions are now updated as part of the group renaming process.
Alternative using SQL queries
Follow the following Atlassian guide in order to rename each of your groups which contain upper-case characters: https://confluence.atlassian.com/confkb/how-to-rename-a-group-and-preserve-its-permissions-948228977.html