I agree; that’s a lot of ammonia remaining. I wonder how that much got there.
Have you been adding ammonia everyday? If so, it’s not necessary, and could potentially explain. Otherwise, I think all the dead rock you used must have had lots of organics that are still decomposing. And I agree with everyone else here. Adding more rock from an existing tank can help to boost your population a little.
Also I applaud your patience. Keep it up!
And while I dislike recommending products/chemicals to add; there are a few ‘waste control’ liquids that could speed up the process of decomposition... assuming that is the issue, which it may not be. And as for different sources for ‘bacteria in a bottle’, I’m a fan of turbostart.
Also; you could use this time to help get ahead on your nitrogen reduction, and do a couple of big water changes. Or add some Chaeto and a good light. But that would all be lower priority.
Otherwise, keep up the continue patience. Small changes and constant monitoring will lead to long term success in this hobby