Howard Miller

This (not surprisingly) appears to be a non-core format. But I couldn't find any reference to it anywhere. Can you check your plugins page for optional course formats? Anyway, this setting is why it looks different.

What's the course format (in the course settings)?

I don't believe that's the case. The unenrolment is done by background tasks that run intermittently. I'd need to try it it to give you a 100% confident reply but I would expect unenrolment to take a "an amount" of time after the unenrolment time is met. That depends on a bunch of criteria, but I would normally expect the order of 10-20 minutes, not hours. If it's the latter, something is wrong. However, again, I'm not entirely clear from your description.

Metacourse sync is yet another task, so that you may find that is another wait beyond the initial unenrol.

Anyway, executive summary... no, it's not instant. It's not meant to be.

This is core Moodle and I thought that trailing commas are part of the Moodle style guide (now).

Anyway, it's not Ahmad's problem.

For the Boost theme!!  It's 4.something. I'm going to say, without checking, that it's 4.6. I don't have either of those versions to check.

 

EDIT:

 

Moodle 3.9

Bootstrap 4.5

 

Moodle 4.2

Bootstrap 4.6.2

 

I was close