I have recently started to experience an intermittent error with list item callouts/ECB menu in a task list I am working with.
When clicking the elipsis against any given item in the task list, instead of the ECB menu items being displayed I get a error message which reads: "TypeError: mediaPlayer.getOverlayPlayerElement is not a function"
Now I have added a couple of custom actions to this List Item Menu, but I do not believe these to be the cause of the problem as they have worked. In fact in the time it has taken me to type this last sentence the problem has 'cured' itself and the Task List ECB menu now appears. However, the problem will intermittently recur.
Has anyone had similar experiences or is able to offer some suggestions as to the cause?
I am working with SharePoint Online 2013.