Hi,
This is an issue. Thank you for bringing this issue to our attention. We apologize for the trouble you are experiencing with our plugin. A bug report is currently open with our development team for this issue.
If you have further information or would like to follow the progress of the report, you can do that here: https://github.com/Yoast/YoastSEO.js/issues/2070. We suggest commenting on it so you may be kept aware of updates. You may need an account in order to post.
In the meantime, you will need to convert the Classic Blocks to Gutenberg. That link provides a way to do that.