Does anybody else have issues with SSL certificate renewals failing on Umbraco Cloud. We currently have 2 sites down because of it. We have tried removing and adding hostnames again, and we are in contact with support, but a day later and having confirmed DNS settings 3 times, we are currently not closer to any resolvement of the issue. So just want to hear if any other is experiencing any issues with this?

I don't think having a CNAME pointing to dns.umbraco.io can be the problem. Did the domain have other DNS records apart from the CNAME?

The DNS setup was as follows: Apex domain has an A-record, since it cannot have a CNAME record, pointing to one of Umbraco Clouds IP addresses. Wildcard CNAME record (*.domain.com) pointing to dns.umbraco.io. Changing the CNAME value from dns.umbraco.io to the root domain solved it. This, along with the fact that there hasn't been any issues with the previous settings until approx. 14 days ago, confirms, at least for me, that there is an issue with dns.umbraco.io, something must have changed. I'm suspecting Umbraco has changed something on dns.umbraco.io because of upcoming changes to Cloudflare IP addresses.