Both in production and betalabs. FF only. Found in FF 44.0.2.

1. Open any Flow board.
2. Click on the ellipsis icon and then on Edit.
3. When editing area is open, without any action, click Cancel.
4. the ellipsis menu becomes expanded again and cannot be dismissed without refreshing the page.

The Console displays:
TypeError: $.data(...) is undefined
stop()
ve.adjacentDomPosition()
ve.ce.Document.prototype.getNodeAndOffset()
ve.ce.Surface.prototype.getSelectionState()
ve.ce.Surface.prototype.showModelSelection()
ve.ce.Surface.prototype.onModelSelect()
ve.ce.Surface.prototype.focus()
mw.flow.ui.VisualEditorWidget.prototype.focus()
mw.flow.ui.EditorSwitcherWidget.prototype.switchEditor/<()
.Deferred/promise.then/</</<()
jQuery.Callbacks/fire()
jQuery.Callbacks/self.fireWith()
.Deferred/promise.then/</</<()
jQuery.Callbacks/fire()
jQuery.Callbacks/self.fireWith()
.Deferred/</deferred[tuple[0]]()
jQuery.Callbacks/fire()
jQuery.Callbacks/self.fireWith()
.Deferred/</deferred[tuple[0]]()
jQuery.Callbacks/fire()
jQuery.Callbacks/self.fireWith()
.Deferred/</deferred[tuple[0]]()
mw.flow.ui.VisualEditorWidget.prototype.createSurface/<()
oo.EventEmitter.prototype.once/wrapper()
oo.EventEmitter.prototype.emit()
ve.init.mw.Target.prototype.surfaceReady()

Note: if some editing is done - the ellipsis menu behaves normally.