After migrating a project from QC 9.2 to QC 10, a few thousand manual tests in the test plan do not appear. What might be causing this?
Did the upgrade assessment tool indicate any problems in the project prior to upgrading?
As the tests exist in the DB, I could only speculate that there was some DB corruption - have you got a backup you can check/reinstate?
... just another Tester ...
Have you checked that there is no filter activated on your Test Plan ? If the filter is activated, it will hide some test cases.
Hope this help,