Changing the link structure for my wordpress site

I would like my link structure to be:

https://mysite.com/rv-insurance/page-name

https://mysite.com/blog/post-name

https://mysite.com/blog/category-name

https://mysite.com/tag/category-name

In my settings > permalinks
I changed my permalink to be Custom Structure: https://mysite.com/blog/%postname%/

On the same page I tried to change my Category Base and Tag base to be:
https://mysite.com/blog/
but it disappeared when I saved. And when I clicked on a category on my blog it went to the correct page, but I got a 404 error.

Any ideas? See here: https://www.rvinsurancepro.com/blog/

if you click on a category on the blog post or the drop down on the right you will get a 404 error. The category is showing up under https://www.rvinsurancepro.com/category-name instead.