Missing top menu on "Posts page" after adjusting Reading settings

Hi,

I made a static front page and added a new page called “blog” that I use as my posts page (done in the reading settings).
I have only one main menu that is shown on all pages.
When I was setting up my new “blog” page I was able to see my top menu – but after I added my new “blog” page as my posts page in the reading settings – my top menu went missing.
Why is this happening? I have no issues on the other pages. It appears to happen when the posts are linked to the “new” page in the reading settings.
I have a Theme Forest Dandelion theme.
Thanks