Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for any inconvenience this issue may have caused you.
In this case, please try reimporting the data again in Rank Math > Status & Tools > Import & Export > Other Plugins, then under the plugin column, uncheck the Calculate SEO Scores option below, and click the Import button.

There’s an issue with the Calculate SEO Scores option upon importing the Yoast data which might hinder the process.
However, if you want to recalculate the scores, then you can follow the steps in this link later on:
https://rankmath.com/kb/rank-math-status-and-tools/#recalculate-seo-score-for-posts
Looking forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.