Hi Frank, I regularly use Scrolla animation on my websites but this didn't turn out to be the culprit. Having rebuilt the project to the same stage, whilst checking every time I added something new, I believe that the problem was caused by a 'Reveal Modal' component I had imported from the library. I had initially intended using this but not happy with the result I changed my mind and decided to use sub-pages instead. Despite removing the component from the project I can only assume that some code must have remained which blocked the links from working.
It's A Kind Of Magic - Always appreciate your input as you know!!