status topic omitted from config payload when declaring multiple HAMqttDevices

[dh-create]

When attempting to declare both a SWITCH and BINARY SENSOR in the same arduino sketch I noticed some strange behaviour - for the second device declared, the status topic (stat_t) was omitted from the config payload which appears to be causing homeassistant to fail to import the sensor. i.e. in the example below, garagedoorZSC wouldn't include stat_t even if I manually included garagedoorZSC.enableStateTopic();. If I reversed the following two lines, 'garagedoorZSC' would now include stat_t but 'garagedoor' would not.

HAMqttDevice garagedoor("11HS002 GD DEV", HAMqttDevice::SWITCH, "homeassistant");
HAMqttDevice garagedoorZSC("11ZSC002 DEV", HAMqttDevice::BINARY_SENSOR, "homeassistant");

Arduino code and outputs from serial for the two different cases:

HAMqttDevice garagedoor("11HS002 GD DEV", HAMqttDevice::SWITCH, "homeassistant");
HAMqttDevice garagedoorZSC("11ZSC002 DEV", HAMqttDevice::BINARY_SENSOR, "homeassistant");
<timestamp etc cutoff in serial monitor>Config topic : homeassistant/switch/11hs002_gd_dev/config
22:48:39.071 -> Config payload : {"~":"homeassistant/switch/11hs002_gd_dev","name":"11HS002 GD DEV","cmd_t":"~/cmd","stat_t":"~/state"}
22:48:39.106 -> Config topic : homeassistant/binary_sensor/11zsc002_dev/config
22:48:39.106 -> Config payload : {"~":"homeassistant/binary_sensor/11zsc002_dev","name":"11ZSC002 DEV"}

// Home Assitant device creation for MQTT discovery
HAMqttDevice garagedoorZSC("11ZSC002 DEV", HAMqttDevice::BINARY_SENSOR, "homeassistant");
HAMqttDevice garagedoor("11HS002 GD DEV", HAMqttDevice::SWITCH, "homeassistant");
<timestamp etc cutoff in serial monitor>Config topic : homeassistant/switch/11hs002_gd_dev/config
22:49:29.900 -> Config payload : {"~":"homeassistant/switch/11hs002_gd_dev","name":"11HS002 GD DEV","cmd_t":"~/cmd"}
22:49:29.900 -> Config topic : homeassistant/binary_sensor/11zsc002_dev/config
22:49:29.900 -> Config payload : {"~":"homeassistant/binary_sensor/11zsc002_dev","name":"11ZSC002 DEV","stat_t":"~/state"}

thanks, Dave