Positive covid test then line vanished?

[Inkdrinker]

Hi all,

I had a faint positive test this morning. Line took about 5 minutes to show up and it was faint but after 30 minutes, the line has now disappeared?

Idk whether to class that as positive or not

Do another one? Maybe leave it a few hours (if you don't need to know urgently for any sort of trip/appointment)