Delete / Edit End condition exception

Hi,

I am using OPenRoads 2020 release2. I had applied an nd condition over ride in my corridor. I did not get any error upon creating . Now after few days i am trying to Edit the extents. I am able to vary the chainage extents . Upon processing the corridor i get a message "Object Reference not set to an instance of an object". The change i made does not happen.

I get the same message upon deleting the End condition exception.  It does ot get deleted. All i am able to do is change the End Condition override to Back Bone Only . I dont want to redo the corridor.

If anyone can throw some light on why such errors happen will be helpful. 

Thanks