I'm skeptical that much of the staff there are actually trained nurses. Pretty much all they have to do give some basic instructions, collect the bag of samples, deliver it to the folks running the test, and give people directions to tents. They do have a medical professional on site to talk with patients who answer yes to something on the questionnaire and have a conversation with the people who test positive, but I suspect that the bulk of the staff there are not trained/qualified to administer the test and that's why they are self-administered.
Inconclusive, in the case of a covid test, is different from "invalid." An invalid test is usually user error (not enough mucus). But an "inconclusive" result usually means a small amount of viral DNA was identified but it was not enough to test positive. In general, inconclusive should be treated as positive pending re-testing to rule out a positive. It can mean OP was either (1) at the tail end recently concluded a prior infection, or (2) at the very start of an infection--e.g., got infected that day or the day before--but tested too early for the virus to multiply enough to generate a positive result (at least at first). In scenario 2, it would be extremely unwise for
DCL to allow you on a cruise ship because you would only become more and more contagious as the cruise went on. Which is why OP was denied boarding.
Just wanted to explain because it seems to be that some people are under the misconception that inclusive means something was wrong with the test or the test takers, when in reality, it was working exactly as intended--flagging a possible early Covid infection that could be confirmed by a subsequent test.
And one positive test plus one negative test is not a tie/draw as someone said. There is actually no such thing as a "negative" or "not Covid" test result, only a "not detected" result, meaning there was no Covid virus in detected
in the sample although you could still have it in your body and it just didn't make it in the swab. A positive test means you do have the virus--there's no real possibility of a false positive except in cases where a sample is switched or cross-contaminated, so that is very rare. And with multiple inconclusives, that is obviously not what is going on here.