This looks like a bug to me, ConversionTypeName segment is not of much use without a Conversions metric :).
I checked all the other report types and only 3 that include ConversionTypeName segment state it cannot be used with the Conversions metric.
Those reports are:
- keywordless-query-report
- keywordless-category-report
- video-performance-report
Is this a bug/design oversight on these reports?
Thanks,
Andrew