I do, the case number is 2017-0516-0819
Actually the second one I've opened about this. Didn't really get anywhere with the first one and gave up. I can't really find somone who knows this feature inside and out and can't really find in depth docs.
I just can't get this to work right. I've also reiterated to our account people (we are a new customer) how important this feature is for us to be able to use Juniper switches everywhere in our environment to the point that it is a deal breaker in some scenarios.
I added "allow-snooped-clients" under forwading-options dhcp-relay ovrerrides on the 3400 and it seemed to help but I can't replicate this on the 4300.