A new bug fix version of Content Studio has been released. It includes a few bug fixes, the most important of which is required to bring back resolution of empty regions in XP’s Content API (which can be enabled again in XP 7.13.1). Full changelog can be found here.
If you are still on an earlier version of XP (before 7.13) and are planning to upgrade to 7.13, then we suggest upgrading straight to XP 7.13.1 and CS 5.0.1.