[bitfolk] Dynamic Updates to BitFolk Secondary

This is a bit out of scope for BitFolk support, but I feel like I'm treading out of my depth a little here. I've setup Bind9 and it's chuntering away quite happily, with BitFolk name servers happily serving up DNS for my little corner of the internet. Now I'm trying to setup a RFC 2136 client for Dynamic DNS, so that my home router can connect and notify the outside world what my current IP is (via an A or AAAA record), so that I can remote in from outside. I'd also like to use wildcard SSL certificates from LetsEncrypt, but that too likes to play with Dynamic DNS these days (TXT records). I know that it's apparently working - I cna see the log entries for Bind9 reporting the new updates, and I see a .jnl file for my dynamic zone. I've setup "notify yes;" for the dynamic zone, and made sure that I only send AXFR (by default, IXFR is enabled, I've tried turning it off but I get the same result), but I can't see if those updates are getting sent (should I see that update going out in the logs?). If I dump the cache, I can see that as far as the master is concerned, everything is complete. Can anyone help guide this poor soul?