Issue loading blueprints that reference an engine plugin (leapblueprintsupport)

I am having a strange problem with loading blueprints that contain references to the leapblueprintsupport plugin, and wondered if anyone else had come across the issue.

Basically I can create a blueprint, add leap specific functions, save and compile and run fine. I can keep doing this during the first session of the editor. If I shut down, then restart the editor, an assert fails in Blueprint::ChangeOwnerOfTemplates, line 972. This is firing because the ComponentTemplates list has a single entry which is a null. I don’t really know enough about the internal workings of this class to fix this, but wondered if anyone else had come across the problem?

EDIT: patching the engine to skip this error, I can get the editor to load. I then get a load of errors about loading /Script/LeapBlueprintSupport. I have confirmed that the plugin is still checked in plugins. Any ideas how to debug this?

Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3897 Property /Script/Engine.EdGraphPin:PinType
Error /Game/Blueprints/MyCharacter : Can’t find file for asset. /Script/LeapBlueprintSupport
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by MyCharacter_C Property /Script/Engine.BlueprintGeneratedClass:ComponentTemplates
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by CallFunc_AddComponent_ReturnValue
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by LeapInput
Info Failed to load /Script/LeapBlueprintSupport.LeapFrameData Referenced by CallFunc_GetFrame_ReturnValue
Info Failed to load /Script/LeapBlueprintSupport.LeapImage Referenced by CallFunc_Array_Get_Item
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by MyCharacter Property /Script/Engine.Blueprint:ComponentTemplates
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by MyCharacter Property /Script/Engine.Blueprint:BPVariableDescription.VarType
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3921 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by K2Node_CallFunction_31806 Property /Script/BlueprintGraph.K2Node:MemberReference.MemberParentClass
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3925 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapImage Referenced by EdGraphPin_3926 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3928 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by K2Node_CallFunction_31841 Property /Script/BlueprintGraph.K2Node:MemberReference.MemberParentClass
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3932 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapFrameData Referenced by EdGraphPin_3933 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapFrameData Referenced by K2Node_BreakStruct_104 Property /Script/BlueprintGraph.K2Node_StructOperation:StructType
Info Failed to load /Script/LeapBlueprintSupport.LeapFrameData Referenced by EdGraphPin_3941 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapHand Referenced by EdGraphPin_3942 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapImage Referenced by EdGraphPin_3943 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapImage Referenced by EdGraphPin_3956 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapImage Referenced by EdGraphPin_3959 Property /Script/Engine.EdGraphPin:PinType
Info Failed to load /Script/LeapBlueprintSupport.LeapInputComponent Referenced by EdGraphPin_3876 Property /Script/Engine.EdGraphPin:PinType