Hi Daniel,
Thanks a lot for your query and we are so sorry about the trouble this must have caused.
Please try decreasing the URL per sitemap limit in WordPress Dashboard > Rank Math > Sitemap Settings > General.
Alternatively, please ask your website host for the error log that can help us determine the root cause of this issue.
We look forward to hearing back from 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.