Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for the delay and for any inconvenience this issue may have caused you.
The Overall Optimization chart shows how well your posts are optimized based on Rank Math’s scoring system and will base its score on the post/page list view in your WordPress Dashboard.
Since you mentioned that the scores are already showing on the post list page, please follow these steps:
Head over to WP Dashboard > Rank Math > Status & Tools > Database Tools and click the Rebuild Index for Analytics
button.

Please note that some options are only available when you enable the Advanced Mode in Rank Math. We give you an option to choose between the two during the setup wizard and you must have chosen to use the Easy Mode.
You can switch to the Advanced Mode from the top-right corner at WordPress Dashboard > Rank Math > Dashboard

I hope that helps. Thank you, and looking forward to your update.
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.