Can't rearrange animation parameters

I can't seem to rearrange my animation parameters. When I try to drag them up and down I get this error.

Any idea what's going on?

Happening since Unity 2018.4.3 ~> Unity 2018.4.5f1

NullReferenceException: Object reference not set to an instance of an object UnityEditorInternal.ReorderableList.DoDraggingAndSelection (UnityEngine.Rect listRect) (at C:/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:707) UnityEditorInternal.ReorderableList.DoListElements (UnityEngine.Rect listRect) (at C:/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:595) UnityEditorInternal.ReorderableList.DoLayoutList () (at C:/buildslave/unity/build/Editor/Mono/GUI/ReorderableList.cs:396) UnityEditor.Graphs.ParameterControllerView.DoParameterList () (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/ParameterControllerView.cs:668) UnityEditor.Graphs.ParameterControllerView.OnGUI (UnityEngine.Rect rect) (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/ParameterControllerView.cs:752) UnityEditor.Graphs.AnimatorControllerTool.OnGUIEditor (UnityEngine.Rect editorRect) (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:1352) UnityEditor.Graphs.AnimatorControllerTool.m_B () (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:1622) UnityEditor.Graphs.AnimatorControllerTool.ScopedOnGUI (System.Action onGUIHandler) (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:1423) UnityEditor.Graphs.AnimatorControllerTool.m_1 () (at C:/buildslave/unity/build/Editor/Graphs/UnityEditor.Graphs/Animation/AnimatorControllerTool.cs:1622) UnityEngine.Experimental.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:266) UnityEngine.Experimental.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e, UnityEngine.Matrix4x4 worldTransform, UnityEngine.Rect clippingRect) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:438) UnityEngine.Experimental.UIElements.IMGUIContainer.HandleIMGUIEvent (UnityEngine.Event e) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:421) UnityEngine.Experimental.UIElements.IMGUIContainer.HandleEvent (UnityEngine.Experimental.UIElements.EventBase evt) (at C:/buildslave/unity/build/Modules/UIElements/IMGUIContainer.cs:401) UnityEngine.Experimental.UIElements.EventDispatcher.ProcessEvent (UnityEngine.Experimental.UIElements.EventBase evt, UnityEngine.Experimental.UIElements.IPanel panel) (at C:/buildslave/unity/build/Modules/UIElements/EventDispatcher.cs:511) UnityEngine.Experimental.UIElements.EventDispatcher.Dispatch (UnityEngine.Experimental.UIElements.EventBase evt, UnityEngine.Experimental.UIElements.IPanel panel, UnityEngine.Experimental.UIElements.DispatchMode dispatchMode) (at C:/buildslave/unity/build/Modules/UIElements/EventDispatcher.cs:307) UnityEngine.Experimental.UIElements.BaseVisualElementPanel.SendEvent (UnityEngine.Experimental.UIElements.EventBase e, UnityEngine.Experimental.UIElements.DispatchMode dispatchMode) (at C:/buildslave/unity/build/Modules/UIElements/Panel.cs:176) UnityEngine.Experimental.UIElements.UIElementsUtility.DoDispatch (UnityEngine.Experimental.UIElements.BaseVisualElementPanel panel) (at C:/buildslave/unity/build/Modules/UIElements/UIElementsUtility.cs:245) UnityEngine.Experimental.UIElements.UIElementsUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at C:/buildslave/unity/build/Modules/UIElements/UIElementsUtility.cs:68) UnityEngine.GUIUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at C:/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:179)