I have noticed a couple of other older posts which involve Electron, Cellular.off() and Sleep modes but they are a bit old. I am using firmware 0.6.0 (latest)
I am finding that if I call Cellular.off() and then go almost immediately into a Sleep mode (not Deep Sleep in this case but it probably applies as well) that the modem does not power off, it continues fast flash of green, ie, on but not connected.
To prevent this it is necessary to insert a delay of at least 6 seconds between the Cellular.off() and entering sleep mode. Then everything works OK.
Thinking about it, this is probably OK, in sleep mode the device does not operate so if it is waiting for confirmation from the modem that it has turned off then it assumes it has not?
Any of you wonderful people close to the firmware able to comment on this?