Hi,
I've tested this, but no strange things, no changes too. I must say that before the plugin was updated, the older version worked as should. The API error keeps on showing. I've removed the WP-Rank-Math plugin and re-installed version 1.0.14. Everything works correct now again with the Site-Wide Analysis. No errors and a complete report. It must be something in the new version 1.0.15 that is causing this error.