[SR-Users] t_on_failure route not being called

Hey all, I'm using a combination of http_async_client and rtjson to query my API and retrieve a JSON target route set for an incoming SIP request that Kamailio will forward to. The HTTP portion of it works great. I'm able to hit my API and get back a JSON document. Additionally, the rtjson parsing appears to work, because the request is hitting my freeswitch instance. However, FS is responding with a 503 (I'm intentionally doing this for testing), and Kamailio isn't calling my t_on_failure route. I've pasted the relevant portion of my config below - would be great if anyone has any insights. tl;dr: the "REROUTE" route section below isn't being reached even when FS responds with a 503. Best, Colin route[ROUTING_REPLY] { if $http_ok && $http_rs == 200 { xlog("L_INFO", "$ci|log|loaded target route set from document $http_rb\n"); rtjson_init_routes("$http_rb"); rtjson_push_routes(); xlog("L_INFO", "$ci|log|attempting to relay request towards $du\n"); t_on_failure("REROUTE"); t_set_fr(0, 1000); t_relay(); } else { send_reply("480", "Temporarily Unavailable"); } } route[REROUTE] { xlog("L_WARN", "$ci|log|relay to destination $du failed, checking next route\n"); if (rtjson_next_route()) { xlog("L_INFO", "$ci|log|additional route found, directing request to $du\n"); t_on_failure("REROUTE"); t_set_fr(0, 1000); t_relay(); } else { xlog("L_WARN", "$ci|log|route list exhausted, failing request\n"); send_reply("480", "Temporarily Unavailable"); exit; } }