Even though the test line is absent?
I've done 3 tests (not all from the same box) and all 3 have a strong line on the C but nothing on the T.
I know in the past these was counted an invalid tests but seems odd to have dodgy ones from different boxes so wondered if it's a new strain of covid?
I do have coldy symptoms and as I visit vulnerable adults, I want to be as sure as possible that I'm ok.
Anyone else had this?