App says Ovulating but no LH surge past few days

I have 2 kids already. Am 41 and me and my new partner just started trying since Xmas. My last 2 were both accidents. This time round decided to try ovulation kit as last month did not get pregnant. And I usually catch quick.

So this is Ovulation week and today is ovulation day. We have had sex 6 times in this cycle and 3 times during this week. I have the physical signs of ovulation eg. Sore breasts, bloating, pain during sex too but no test line on ovulation strips at all. I have been using Wilko strips. Has anyone else experienced this? I bought another brand from home bargains and still same. Started testing twice a day. Still nothing.