Every human is built different. If your not in ketosis, either 1, your strips are not good or 2, your body is using your muscles instead of your fat storage. Try to do a 96 and do the test again. If it still doesnt work, dont go longer than 96 and talk to your doctor.
I know you found the issue was dodgy strips, but remember the following. Those things only show you the ketone levels in your pee. The more ‘adapted’ you become, the less ketones end up in your pee, as your body is better at using the ketones. Someone who is well adapted could be super deep into ketosis and the strips wouldn’t show it.
Sometimes you just need to go longer and you did have a carb heavy meal before starting. That turns into sugar which your body is still processing. I show the most ketones after a protein heavy meal and after a while when I do have carbs I will jump back into ketosis faster. Don’t get discouraged! The strips are sometimes faulty