I never had an issue with the Clear Blue tests and always got flashing and then solid smileys. If it continues to be an issue for multiple months then you might want to check in with your doctor about concerns that you might not be ovulating. Best of luck!
I’d really recommend trying cheaper strip tests! They’re a lot more precise for gauging your actual peak and the run up to it! You could get over a week of flashing smileys when in reality your LH is still really low or you could get a LH peak and the clear blue not register it as it didn’t reach the threshold. Worth a try!