Back and next does not display

Great plugin, but have on problem. If I choose “Number of events” in the “Events per Page” drop-down menu in the feed settings, for instance 5 like I do now on my page, then the “Back” and “Next” button disappears. But if I choose “One week”, then they are there.

https://ww.wp.xz.cn/plugins/google-calendar-events/