I've ran into a strange problem today.

I created a new custom post type, "blog". Everything appears to be working correctly. However, when I make a new comment on a post under this new custom post type, the comment is instead sent to another post of mine, which is of the default type.

The comments show on all posts of the new custom type, and on the old post. The backend shows no comments on any posts of the custom post type, however.

Deleting the old post which recieves the comments simply assigns another old post as the unlucky reciever.

The comment submit button points to the wrong ID on all posts of the new custom post type.

What's going on? How do I even begin to debug this?