First of all, in order for the Test Execution status to say Passed or Failed, all tests and steps must say ''passed'' or ''failed''

If you have multiple ''test configurations'' for any of your tests in the Test Set, these may be the ones that report ''Not Complete'' for the Test Execution Status.

By default, when you establish test ''coverage'' between a Requirement and Test, it is for the ''whole'' test, meaning that it includes all of the test's configurations.
Normally, there is only one configuration for each test (it has the same name as the test), but if someone creates any additional configurations (to use the same test for different browsers, for instance), it shows up in the test's configurations list and when you add a test to a test set, QC asks which configuration to use.

When you look at the Traceability Matrix or other coverage related reports, it may say ''Not completed'' for a given test -- even though the one if the test set has passed. This is usually because the other test configuration(s) are not also passed (usually say ''no run'').

In order for the Test Execution Status to say Passed, ALL configurations for a given test must also say passed for the test status.

So, to resolve this issue, EITHER don't use more than one (default) test configuration, OR make sure your Requirement/Test coverage is explicitly defined for a specific Test Configuration instead of just generically pointing to the test and being associated with ''All configurations''.
When the coverage says ''All configurations'', which is the default, then the Test Execution Status will indicate ''Not Completed'' until all test configurations for a given test all say ''Passed'' or ''Failed''.