WordPress Custom post type slug rewrite

I had to face a similar issue a while ago and got it resolved by following this guide.

Basically what you have to do is two functions 1) Custom WordPress Rewrite Rule and 2) Custom Post Type Link.

The Rewrite Rule function will make sure the custom slug for your CPT is handled properly throughout the site. And the second function will ensure that it displays the URL the way you want – you can also include taxonomy variables if you wish to. Anyway take a look at the article as it helped me a lot and I hope it helps you too as well.