@derchris does that graph only represent the current draw from the Electron? Are there any other peripherals or sensors connected to that power source/graph that might draw power? If there are, are those peripherals connected directly to the power bus or via an Electron power pin?
The first time you cold boot an Electron in SEMI_AUTOMATIC or MANUAL mode you need to turn the modem on before going to sleep. This is counter-intuitive, but putting the modem to sleep is done by sending AT commands at it, so if you don’t turn it on, it stays half-awake because it doesn’t get the command to sleep.
Note that you only need to do this on cold boot. I use a retained variable to know this. If the modem was previously asleep it will stay asleep.
This post is for SLEEP_MODE_DEEP but it also applies to stop mode sleep with cellular off.