Is it not possible to enroll into private events which are a part of a private course?

Summary:

Hi Experts,

In relation to a business case we created a private course and made assignments to a few people. This private course also has private events and user group has been added to it to restrict visibility on the events. While trying to enroll into any of the events as someone who is part of the user group, the select/enroll button is greyed out, even though the events are future dated. Is this an expected functionality?
In case the event visibility is changed to open then the select button is activated.

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