When I add elements or resources to the course, the course id is always equals 1 and all the added elements attached to the course with number 1 (system cource or front page). This is displayed in the parameters in the browser line and in the database tables.
There are no errors. If you correct the course id wherever you need in the database, then everything appears in the right place.
This happened after the moodle update (which version I can't say for sure, I didn't notice right away).

I found that another people have the same problem from moodle version  3.11.2+ but problem stil don't solve.

domain_name/course/modedit.php?add=page&type=&course=1&section=1&return=0&sr=0