Mine said it had stopped publishing yesterday at 05.59am. When I got back the lights all seemed ok, but I reset it and re paired it with my WiFi. Didn’t make any difference, so I connected via the SDK via USB and saw that it WAS publishing every minute) to somewhere which seemed to be sending back an acknowledgement and also issued the “hello” command which pinged the server and got a positive response, so I will stop fiddling until, what sounds like the server, is sorted out . See below
SCK > PM 1.0: 1 ug/m3
PM 2.5: 1 ug/m3
PM 10.0: 1 ug/m3
(2019-08-05T08:42:20Z) Sent 9 readings to platform.
(2019-08-05T08:42:20Z) Readings saved to sdcard.
(2019-08-05T08:42:20Z) Published OK, erasing from memory
Waiting for MQTT hello response…
SCK > Hello OK!!