Update from Particle, 5/7 at 3:30pm PDT:
The engineering team at Particle has spent the majority of the day investigating this issue to identify a root cause for devices that are still unable to reconnect to the Cloud. Although the caching system that crashed has been successfully restored, there are some devices that are still unable to successfully establish a new session.
We believe that devices affected by this issue are unable to restore their session with the Cloud due to lost session data from the caching system crash. The session restart logic in Device OS is not able to trigger a new handshake attempt before the device goes back to sleep, and the device may get stuck in an endless session restore attempt loop.
As Matthew stated previously, the only presently confirmed fix to force a device to re-handshake is to fully power cycle the device (a soft reset is not sufficient).
Our engineering team is currently exploring options for Cloud-side resolution that will help devices successfully restore their connection without the need for physical intervention. We will continue to provide updates on successful remote resolution strategies if and when they are available to us.
In the meantime, our support agents are working to determine the scope of this issue and assist customers with devices that may be suffering from this or other unrelated connectivity issues. If you have any specific device inquiries, please feel free to reach out to our team at support.particle.io