When editing a course event the Event Type is changed automatically and can't select Course as Event Type anymore.

Steps to reproduce the original issue

1. New steps to replicate

2. Login as admin.
3. Make sure calendar_adminseesall admin setting is turned off by default.
4. Make sure the admin user is not enroled to any course. If yes, please unenrol.
5. Create a new course.
6. Make sure to unenrol the admin user out of the created course (If you are using Moodle 4.0).
7. Navigate to the created course and add the Upcoming events blocks.
8. Click Go to calendar... in the block.
9. Click on New event button.
10. Set the Event title to "Test course event".
11. Press Save button.
12. Click on the cog icon next to the created event to edit.
13. Observe the Type of event field.

Expected result:

1. The Type of event field is set to Course.
2. The course name of the event is also shown.

Actual result:

1. The Type of event is set to User.
2. There is no Course option in the Type of event Combobox.
3. The course name of the event is not shown.

-{}Original steps to reproduce{}-

Steps to reproduce:

1. Logged in with Admin
2. Go to a course and add the Upcoming events block and then click Go to calendar...
3. In the upcoming events view, click New Event to create a new event for the course.
4. Add a title and set a date in the future when creating the new event and save.
5. In the list, on the page with events, click on the cog icon next to the event we just created for Editing the event.
6. The Type of event is not Course anymore. The only available options are: User / Category / Site.

After Saving a new event created when you try to edit it, the Course disappears from the list, and the event won't show up under the course anymore.

Everything is done with the admin user.

I have tried a fresh new install of Moodle, the latest build 20210827, same outcome.