Hi Stuart, 

There isn't a way to do this at this time due to the size and nature of the queries required, it would make the reports too large to run and have timeout problems.  

You can post an idea to improve this on our User Voice page (https://nintex.uservoice.com/), otherwise I image that this information may be included in a future release of our reporting API and you would be able to use this.  @KerryHiki Can you confirm if adding this information to the Reporting API is on the roadmap?

No plans for the next 3-6 months, but it will be something we'd make available through the reporting API. Based on UserVoice feedback it may be put ahead of other data points.

Thanks

Kerry