Do note that if the account has no campaign, then there are no ads to generate impressions. This could possibly be the reason why you're not getting any rows where performance data/metrics are included in your report. If you wish to include zero impressions in your generated report, then you may set the
includeZeroImpressions HTTP header to true.
However, please note that some fields doesn't support zero impressions so if you include them in your selector, then it might produce an error when generating the report where includeZeroImpressions is set to true. For example, for Account Performance Report,
ClickType field does not support zero impressions so if you include it in your report definition with includeZeroImpressions = true, then an error will be thrown.