While testing https://tracker.moodle.org/browse/MOBILE-2746 in master (3.7), you set up a "Page 1" with automatic completion when viewed. When you visit the page (in step 17) using the App it doesn't get checked neither it is updated the %. If you visit the Web, it shows the checked there and then if you PR the App then the check is shown in the App.

[I checked with a 3.6 site and it works there]