Next.js getStaticProps revalidation not working all of a sudden?

Question

I have author pages with the following getStaticProps:

export async function getStaticProps({ params }) {
    const { slug } = params;

    try {
        const FILTER_URL = `${process.env.NEXT_PUBLIC_API_URL}/authors/?slug=${slug}`;
        const filter = await axios.get(FILTER_URL);

        const AUTHOR_URL = `${process.env.NEXT_PUBLIC_API_URL}/authors/${filter.data[0].id}/`;
        const author = await axios.get(AUTHOR_URL);

        return {
            props: {
                data: author.data,
            },
            revalidate: 10,
        };
    } catch (error) {
        return {
            notFound: true,
        };
    }
}

I've updated the data for an author page - and I can confirm that the backend AUTHOR_URL has this updated data - but the frontend does not update or revalidate.

I've also set up on-demand ISR revalidation set-up and manually revalidating the page returns {"revalidated":true} but the frontend remains the same.

It looks like any changes to an author page that I make today is not being updated or revalidated. However, I made changes to author pages yesterday and they are updated (and I have not rebuilt next.js in that time.)

Does anyone know what the issue might be here?

Is it possible this is just a temporary issue with my provider DigitalOcean's CDN?