Scheduled reports (PDF) sometimes show corrupted charts

I have about a dozen scheduled reports every month, and every time there is at least one that shows for one or more random fields an error in the attached PDF. These Reports also go to clients and it is very unpleasant every time that happens. Some clients ignore it because its routine, some joke about it, others complain, but this is an always recurring rememberance of the inadequacy of Google products. Think about that: every month my clients and myself get proof of Lookers unreliability. Isn’t that disturbing?