A locked entry is one that can no longer be edited, because the task's due date has passed and the record has closed.

Nothing is deleted when this happens — the entries are all still there and still counted. What ends is your ability to rewrite them, and that is the point: time records feed invoicing, reporting and pay, and a record anyone can revise later is not a record.

The fix is upstream. Log time while the task is still live, ideally the same day. If it keeps happening, the due dates are probably too optimistic rather than your logging too slow.