Unlock a page locked by a nonexisting user
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.
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.