There is a page locked by a user who is no longer in the system. As superuser the page is not locked, but the page is locked to everyone else. You have tried to lock/unlock it as superuser. However, the page is still locked for everyone else.

Solution

As superuser, access the CRX Content Explorer and navigate to the page in question. On the cq:content node under the page, delete the properties PageLockDate and PageLockUser.

To synchronize CQ with CRX, access the page in question in CQ with the superuser. Then, make a small change to the page. Saving the change synchronizes CQ with CRX. Afterward, revert the change.