Odd issue with the page title

A bit weird but when you go into a category it says in the title what the category is, but you go into the post and the page title becomes “Blog”, which is odd. It happens on all posts.
I’m quite able to make a child theme to sort it, but, well, I just can’t be bothered and would prefer the theme didn’t act odd.

The page I need help with: [log in to see the link]