Long shot- first Vue/Poundland ovulation tests?

I've been using these pretty much the last 3 cycles with what seems to be no issues. This cycle though my tests iterally have no second line, some do, most don't. I noticed they're a slight difference between the batches (confirmed with checking batch code). One batch has a darker colour blue holding strip and the other batch is slightly lighter blue. Looking back on previous month's all the others have been the darker blue ones. I noticed the lighter blue ones are the ones that come up rarely with a second line.

I was just wondering if anyone else has been using these recently and noticed similar results? Im sure it's just me and my body still being broke but I thought I'd ask for a slight bit of hope 🙃