2 Widgets are shown as not found: https://demo.matomo.org/index.php?module=CoreHome&action=index&idSite=3&period=day&date=yesterday
Not sure if only a problem on demo or in general
The empty widget appears to be for a goal that doesn't exist:
widgetGoal_10, not sure what could cause that, maybe a goal was deleted?
The other widget has a uniqueId of
widgetReferrersgetReferrerTypeforceView1viewDataTabletableGoalsdocumentationForGoalsPage1idGoalecommerceOrder, not sure if this is expected or not. Wondering if it would be good to revert demo to 3.5.1 and see if the bug remains. If it's not a regression, then I don't think they're blockers for 3.6.0.