Pulling random post instead of specified category

I had this problem and it was because I had changed the category names but the slug remained the same. Not sure if it was specific to my theme but maybe it will help.

Go to your list of categories in dashboard. Rather than clicking the category to get the slug choose view. See the URL. Copy the slug from there. Mine were different to the ones that were displaying in the other option.

I also just pasted the slug into category name and left the category ID blank. I then deleted the category id from the shortcode and pasted this into my page.

Hopefully that helps.