We're working on migrating some of our API code and it looks like you
bumped into something I missed when doing that migration. The good news
though, is that now that you've found it, I've fixed it and you can now
do API calls like this again:
https://atlas.ripe.net/api/v1/measurement/?dst_asn=3333
As for the measurements that don't have an ASN value, we're looking into
that, but there are a number of legitimate reasons for their not having
one, including having no target specified (some DNS measurements for
example).
