Results arrive per test, within the hour of each one being submitted. If something is missing after that, it is one of four things.

1. They have not actually submitted
By far the most common. Open the candidate and read their progress: it says how many tests of how many have been submitted.
A candidate who started a test and closed the window has not submitted it. There is no partial result for an unsubmitted test, and there cannot be.
Send them a reminder from their row. Their finished tests stay finished.
2. The result is locked, not missing
Look at the score column. Locked means the result exists and has not been unlocked for your organisation, because your free allowance is used and there is no prepaid balance or saved card.
Nothing is lost and nothing expires. See unlock results and check your usage and balance. The awaiting unlock figure on the billing page tells you how many are waiting.
3. They are on the assessment under a different address
If a candidate was invited on one address and registered through your shared link with another, there are two records: the invitation sitting untouched, and a separate candidate with the results.
Search Candidates by name rather than by address. You will usually find them straight away.
4. They took a different assessment
Easy to do when you have duplicated an assessment for a second round. Check Candidates with the assessment filter cleared, then look at which assessment their row names.
Personality and drives
These are not scored and produce a profile, not a percentage. A dash in the score column for one of them is correct behaviour, not a missing result. The profile is in the candidate's report.
An assessment made only of unscored questionnaires has no overall score at all, and the report says so.
If results are still missing
If the candidate is certain they submitted, the result is not locked, and you have checked the address and the assessment, tell us. Email support@testcandidates.com with the assessment name, the candidate's email address and roughly when they finished. That is enough for us to find it.