RaidXUL

WordPress creates a .maintenance file during the update process which indicates that your site is in the maintenance mode. Unless this file is removed your site will remain in the maintenance mode and your users will continue to see the notification.

Soundforscher you mis-understand how AMP pages work.

When you use amp plugin It wont detect device an kick to AMP page; It adds AMPHTML href url to the page which google picks up on; Upon which it serves via its SEPR pages.

AMP pages are not included on sitemap;

They are included on orginal post page; Which google crawls automatically to find the AMPHTML url.

<link rel=”amphtml” href=”https://www.domain.com/article/amp/”/&gt;

Googles reindexing can take between 1-4 weeks depending on how active the website traffic/signals are.