Editor Menu item insert limit Workaround?

I have an enum which has reached a size that the editor no longer wants to populate all the elements in the menu. It gives the the error: Failed to insert item. Menu item insert limit is reached. -Listing only part of the full enum that is otherwise accessible.

Could someone please point me in the direction of getting around this limitation and displaying all the collection elements in the editor menu.

Where in the editor? Custom editor? How many items? Why does it have so many? Can they be combined? Is splitting the enum an option?