EnumPopup behaves differently than the default inspector and previous versions of unity, and breaks with "/" in names.
1. What happened
EnumPopup behaves differently than the default inspector and previous versions of Unity.
It shows the DescriptionAttribute instead of the name and breaks if the description contains "/".
The description attribute is fairly common in third party libraries and often includes "/"
E.g., The SteamVR_Input_Sources enum in: https://github.com/ValveSoftware/steamvr_unity_plugin/blob/master/Assets/SteamVR/Input/SteamVR_Input_Sources.cs
2. How we can reproduce it using the example you attached
Open the EnumTest scene and select the EnumTest GameObject.
Try each of the Enum Test popups.
The first is the default inspector (and same as EnumPopup in previous versions of Unity).
The second is a broken Enum Popup.
License type: Pro