There may (or may not) be an issue with the changes Google made back in February around consolidating around the canonical URL, which means the AMP, mobile, etc will all be counted towards the main URL’s data in the performance report. This may not be happening correctly for some sites and Google is supposedly investigating this issue.

Fabio Assis asked John Mueller of Google about the issue and posted this screen shot on Twitter:

Pedro Dias, who is a former Googler, and a top contributor in the Google forums responded that this may be an issue and Google is investigating it. He said:

John later asked Fabio for the URL to investigate:

Nothing is yet confirmed but there may be issues with the Search Console performance reports, we will let you know if and what Google says, if they do.

Forum discussion at Twitter.

Update: Here is the latest on that topic: