Tradfri switch E1524 issues

I have an old E1524 switch. I am using the Hassio Add-on for zigbee2MQTT and one of the Node-RED dashboards.

I have managed to pair the device and change the friendly name, it appears in Home Assistant, but says unavailable. I cannot get any button press to elicit a response and there are apparently no MQTT messages being generated.

What might I be doing wrong?

	"ieeeAddr": "0x90fd9ffffe739b4c",
	"type": "EndDevice",
	"networkAddress": 7221,
	"model": "E1524/E1810",
	"vendor": "IKEA",
	"description": "TRADFRI remote control",
	"friendly_name": "IKEA Switch1",
	"manufacturerID": 4476,
	"manufacturerName": "IKEA of Sweden",
	"powerSource": "Battery",
	"modelID": "TRADFRI remote control",
	"hardwareVersion": 1,
	"softwareBuildID": "1.2.214",
	"dateCode": "20170302",
	"lastSeen": 1586775974045

Will this OTA update?

As a matter of interest the last seen time is in milliseconds (rather than epoch seconds) so this could be causing an issue with HA.