Event permalink does not use Global Permalink settings

In Settings > Permalinks, I’ve set up my permalinks to be structured this way:

/%post_id%/%postname%/

In the Events Calendar Settings, the option “Single event URL slug”: event .

The resulting url should be: event/{ID}/{postname} but instead it is: event/{postname}

I’ve tried flushing the permalinks several times: the issue remains.

Is there something I’ve overlooked? If not, I would assume that this is a bug.