I know when others have had this same issue, we all try and figure out what could be stalling things. Every tank is different and some take longer than others, but I agree - almost 2 weeks is a bit long to see no drop in ammonia for fishless cycling. I'm wondering whether reducing your ammonia to 2ppm might help? You could try a small water change and see what happens.
It happens that sometimes people dose too high for their tank size and their ammonia never drops.
Haven't touched the filter either. I think I will bring the ammonia down to 2 ppm with some new water and a dose of Prime.