The DbContext will be stale at this point, if you continue to use it after running the stored proc. According to this answer (https://stackoverflow.com/a/18830466/3294324) you may be able to update your context without creating a new one.
You could try something like this:
var Context = ((IObjectContextAdapter)_ctx).ObjectContext;
Context.Refresh(RefreshMode.StoreWins, Context.ObjectStateManager.GetObjectStateEntries());