Yeah, a safety release/breakaway collar is great if you want to always have tags on your dog but minimize the risk of them choking if the collar gets caught in a crate, a branch (should they have yard access or get loose), a fence, or another dog's jaws. Which does happen. But they're definitely not meant to attach a lead to.
Sounds like you're doing well! You may find his recall improves as you build your relationship - it's hard for an environmentally focused dog to find a person they barely know and haven't bonded with valuable enough to leave a good sniff for. It may never be perfect because hounds are hounds and they're just hard-coded for the environment to be more important to them than their handler, but I bet you'll keep seeing improvement!
Sounds like you're doing well! You may find his recall improves as you build your relationship - it's hard for an environmentally focused dog to find a person they barely know and haven't bonded with valuable enough to leave a good sniff for. It may never be perfect because hounds are hounds and they're just hard-coded for the environment to be more important to them than their handler, but I bet you'll keep seeing improvement!
