The Wifi strength (as measured by devicevitals) is good, and always at a 100%.
I keep seeing these spark status and particle device update cloud messages that sometimes interfere with publish commands containing sensor data (leading to some of them being dropped. Does anyone know what these cloud messages are and what they do?
I don’t believe that these messages interfere anyhow with the Particle.published messaged by your own code. spark/status offline/online are in fact published by the Particle cloud itself to indicate that the device went offline or online. From the attached screenshot it looks like your device is restarting for whatever reason and thus the missing published messages you’ve mentioned.
The messages are not the cause of your problem, however they indicate a different problem.
You device is going offline (spark/status offline). During the time that it’s offline it won’t send or receive publishes. It’s offline for at least 26 seconds, which is long enough for a publish to be lost, as the timeout is 20 seconds. The rest of the events are just the side effect of coming back online.