I managed to do DNS validation for serveral .com domains, but one with .fi wasn’t successful. This one is also defined as off-site domain in GoDaddy DNS service. Godaddy API can create a TXT record successfully, but reading the TXT record fails. Here are screen shots how it looks.
Without knowing you real domain I can’t diagnose anything but if your DNS (all authoritative name servers for that domain) have the correct TXT record in place when Let’s Encrypt looks for it then it should work OK.
It appears from your DNS control panel screenshot that it created the TXT record OK and that validation failed when Let’s Encrypt tried to check your domains DNS server.
This can either be because not all the name servers involved had time to propagate the change however as you have flagged the 'off-site’nature of the domain I suspect that’s related somehow.
If you would like me to investigate more please email support at certifytheweb.com with your domain details.