It's a weird one.
Two weeks back my daughters boy friend caught it despite rarely going out, they were both tested, he had it, she didn't. The local health authority asked if they would be part of a study and they agreed.
They sent two fully togged up health workers round to take bloods swabs and to test all surfaces, left them with sample bags for all body wastes. Then they got the results, he still had it she didn't.
A week later she fell ill, sore throat feeling grim, in bed for two days sweating, they came round again, rinse repeat. The results came back, he still showed she didn't, she just got the results of a third visit, same results and they implied she was just having sympathy pains, now she isn't the hysterical type and is adamant she had what he had but the health workers are having none of it, she's a bit pissed with them.
Now my wife works as an infection control nurse for our local health service, and early on in this she was training staff how to properly fix masks, which involved the trainees donning a hood with the mask on and she would introduce a saccharin spray, if they could taste it they failed, as a precaution after they passed she would ask them to break the seal on the mask partly to give them confidence that they worked but also because about one in a hundred people can't taste the saccharin, in this case they were asked to do it again with something called bitterex, which as the name suggests is foul.
A couple of them couldn't taste either which was unprecedented (she'd done this many times before for staff on acute wards), when she asked them if they thought they had had Covid, they said yes but they had been tested and it had come back negative.
This is anecdotal but she has checked around and quite a few of the other trainers have had similar stories, when she asked the medical officer about this they too wouldn't give it credence.