Migrating bootstrap to v4 - popovers not working

I've faced the same problem and found solution, here is my popover directive

angular
.module('app.ui.popover', [])
.directive('bsPopover', function () {
    return {
        restrict: 'E',
        replace: true,
        template: '<span class="a-info" ng-bind-html="label"></span>',
        link: function (scope, element, attrs) {
            var el = $(element);
            el.popover({
                container: 'body',
                trigger: attrs.trigger || 'hover',
                html: true,
                animation: false,
                content: attrs.content,
                placement: attrs.placement || 'auto top'
            });
        }
    };
});

and what I did next was changing default placement from 'auto top' value to 'top' and it works for now :)

As far I understood, now you can specify only one of auto | top | bottom | left | right.

Let me know if that helps you :)