Blog problems

hi,

I could really use any help you can offer I’m very new to wordpress and I’m not to sure how to fix what i’ve done.

So, I updated a blog for a company I work with. I made a new blog page for the site and added a custom sidebar to this page, the only problem is that the sidebar doesn’t show up. I think it is a url error as the url for the blog page is

https://www.newmarketconsulting.ie/blog/

but the posts only properly show up in

https://www.newmarketconsulting.ie/category/blog/

Does anyone know how I can fix this? Thank You!