I am using NOF 12.0. The sitemap generated shows the default date of <lastmod>1969-12-31T16:00+00:00</lastmod> under the <url> section for each of the site pages. Google Search Console says this is an invalid date.

Is the sitemap automatically generated? If so, why isn't the date set the date of publishing. If not, how can I set the date globally for all the pages?