Piano-Black theme navigation missing out pages

Hi there,

I’m new to wordpress and php but have been muddling through. I installed the piano-black theme a while ago annd have had no troubles with it till now. I have a large quantity of pages and products and I still have to add more. The trouble is that now if I add any page to the menu either sub or main the navigation bar will drop the latest top level page. It is like I have reached a critical amount and will not be able to add any more. Is this the case with the theme? I expect it isn’t but I’m completely at a loss as to why this is happening. Can anyone give me a pointer as to what may be causing this?

I had some trouble with a plugin that I think caused a conflict with another. I deactivated this and deleted it and thought that this had solved the problem. Could this page thing be related to that?

Any help would be much appreciated.

Thanks,
Olly