The ammo lock is locking the ammonia so it becomes unavailable to the bacteria, then it starves and dies off, In result the cycle never starts.
at this point your cycle probably hasnt even started due to the ammolock starving the bacteria. The only thing you can do is stop using the ammolock and use prime as water conditioner with daily 50% water changes.
or you can use Tetra Safe Start which is bottled bacteria.
also the changing of filters probably got rid of whatever bacteria you might have had.
here is my article covering all of the topics like ammo lock... prime... tetra safe start... hope it helps:
http://www.fishlore.com/aquariummaga...um-startup.htm