I came across a report but on the website I found it, it states that the terms of use are CC-BY. However when attempting to add this report to the policy documents the options we have are CC-BY 1.0/2.0/3.0 etc. Given that there are no numbers on my report should I upload it simply under CC-BY 1.0?

Yes, please do that and in the internal comments state the very same issue.

Thanks!