Disappearing positive. Faulty test?

I’m maybe 9/10 dpo

Took FRER today. First picture was at the 3 minute mark as stated by instructions.

The second picture was 5 minute mark (slightly brightened to show on camera)

I swear I saw a faint line within the time limit and it had colour.

Came back to the test maybe 45 minutes later and it’d gone? Looked negative? 🤷🏼‍♀️

What’s happened? I plan to test again in a few days - just wondered if this was a common thing?!

Thank you