360dialog API returns the following response in this case:
"developer_message":"Template could not be submitted. Error. ","http_code":400,"success":false
We observed that these errors usually appear for templates that use non Latin characters – like templates with Cyrillic or Arabic letters. One of the potential ways to solve this is to shorten the text in the template or remove one or two cards from carousel template.
We are following up with Dialog 360 for this.
Their engineering team is still working on resolving the issue.