Hello,
Generally, the following points may cause the issue;
1. A third party plugin
2. Assigning a deleted/traced page as a static page
3. Permalink
4. Server.
But please don’t worry, we will figure it out and fix or we will let you know if it is related to out of theme area. Please send us your site URL, WP admin or Hosting credential at [email protected] Then, leave us the rest part.
Thanks.