If you’re having problems migrating from on-prem to Cloud, we may need your on-prem logs to troubleshoot the issue.
Please follow the steps outlined at https://confluence.atlassian.com/doc/configuring-logging-181535215.html to set the logging level to DEBUG on com.atlassian.migration and on com.atlassian.plugins.confluence.markdown.
Then reproduce the failure and collect a support zip as outlined at https://confluence.atlassian.com/support/create-a-support-zip-790796819.html and provide it in the support ticket you have filed with us.