Hi @Tristan_Adlington, thanks for your post. There should be a reason why the sitemap is not being indexed, it might be there was already a noindex setting on the domain at some point either through a noindex as a meta tag or previously used with the domain hosting on another service with the robots.txt set to disallow indexing.
I can see that the sitemap is accessible on the site at the correct url and there are no other directives which are published by Webflow to prevent the site from indexing.