Calendar grid is displayed, but no events are shown

I am trying to show a private calendar on a page.
The setup is ok (Verify OK!). I can see calendar ids in the Private calendar settings section.
I am using a shortcode [pgc calendarids=”[email protected]”]
(I hide calendar ID here for privacy reasons)
Result: Calendar grid is displayed, but no events are shown. No javascript errors or messages

The div in the source looks like this

<div data-calendarids='["[email protected]"]' data-filter='top' data-eventpopup='true' data-eventlink='false' data-eventdescription='false' data-eventlocation='false' data-eventattachments='false' data-eventattendees='false' data-eventcreator='false' data-eventcalendarname='false' data-hidefuture='false' data-hidepassed='false' data-config='{"header":{"left":"prev,next today","center":"title","right":"dayGridMonth,timeGridWeek,listWeek"}}' data-locale="en_US" data-theme="" class="pgc-calendar"></div>

Please help.