Posts Nav Bar not working

Hi,

I used the following code in my child css to hide the previous & next post navigation in a single post and it worked fine.
.post-navigation {display: none; }

However, I have decided to have the navigation back in and removed it from the child css, refreshed, cleared cache etc and it will not come back. Should I be doing something else?

Such a silly thing, but I can’t fathom it out!

my site is https://www.helenajohnson.net

Thanks