Numerical permalinks

https://codex.www.ads-software.com/Using_Permalinks

When you use anything than default, 2) can be simply done in the edit post screen. I suppose you can just use %post_id% as permalink.
Make sure your server has all requirements. This should not have much to do with your theme (which theme are you talking about anyway?)

Sorry, Roy. The theme’s https://getqualitycontrol.com/ as per the tag.

The theme can hardly have anything to do with anything. I’ve never heard of a theme with hardcoded permalinks. Follow my links, especially the second one to start with (requirements).

It sounds like this may be a plugin issue:

https://www.ads-software.com/support/topic/permalinks-on-tickets

Try deactivating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.

You can’t have custom permalinks with custom post types (if I recall correctly.)