Every now and then you hear complaints or questions from SEOs that the reports in the Google Search Analytics report is wrong. In that, it shows keywords that they rank number one or two for, and they are getting a lot of impressions for, but that when they look, they really do not rank all that well for.
We covered before how sometimes filtering down that report to show data from as specific country or device, etc would reveal that the traffic and keywords are not coming, for example, from Google USA but rather a regional version of Google. So when you look at Google.com you won't see your site ranking for that keyword but when you go to the regional version, you would.
But John Mueller of Google said in a Google Webmaster Help thread if all that fails, it also might be related to maybe an image of yours showing up in a featured snippet or knowledge graph entry. As you know, featured snippets can source different images from different web sites, so that can really sometimes impact your search analytics reports.
It is always nice seeing these types of responses from Google because it gives you more insight into dealing with these questions when they come up for your site or client sites.
Forum discussion at Google Webmaster Help.