Scope start and end nodes are not in the same workflow.
I use DB Transaction start (in one metanode) and DB Transaction end (in another component). I need the transaction unit in order to make sure that either all or no updates are made within database!
I have managed to solve my problem in a way that DB transaction start and DB transaction end are outside of components.
I cannot show the workflow, but the concept is the same as on the screenshot below: