Problem with numbered titles

The chapter titles are numbered. The first one starts at 61.

I don't know what the issue is but the next chapter title starts at 3.

Then 4, 6, 4 ,4, 3, 3, 3, 8.

It's very strange.

I've convereted them to no paragraph style and reaplied the chapter title style.

I don't know why it is behaving like this.