Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
It sounds to me you got hit by an algorithm update and I am sorry that Rank Math would not cause a drop in rankings.
Refer to these articles:
https://www.searchenginejournal.com/december-2020-core-update/391254/
https://www.seroundtable.com/google-algorithm-update-january-12-30748.html
If a URL is on Google, there is technically no reason for it to not be included in Bing unless Bing has some reason to not index a page like DMCA, copyright content, nulled content, copied content, etc.
I would request you to contact Bing to know the exact reason as from checking the page source, there are no apparent issues.
You could also try various site audit tools to check if there is any issue with your websites.
I hope this helps. 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.