Cant drop multiple images onto IList

I have a simple content reference list for images defined as below:

        [Display(
            GroupName = SystemTabNames.Content,
            Name = "Images",
            Order = 10)]
        [AllowedTypes(typeof(ImageData))]
        public virtual IList<ContentReference> Images { get; set; }

For some reason on-page editing only allows me to drop one image at a time on this property. The moment I select more than one, it does not allow drop anymore. The drop area disappears. The only way I can drop multiple is if I click on the edit area and the editor pops up, that does allow multi-drop. Its quite annoying to my editors.

This does work however for a ContentArea property. I tested with both but I dont want all the extra features ContentArea brings with it. Any ideas on what I can do to improve this experience? Is this a known issue?