Clear blue digital ovulation incorrect??

Bella • BFP 12th May @ 9 dpo. Baby no1 due Jan 2020!! Eee 🤰🤞😍👶

Can Clearblue digital ovulation tests show a solid smiley on the incorrect day? This is our first month TTC and my periods are regular like clockwork (30 days cycle so I should ovulate day 16) however this month I got a solid smiley on day 12 which would give me a 26 day cycle.. so confused! 😊 Thanks so much xx