I've had exactly this happen. After charging both cars overnight on 'Go' there was then a four hour power cut following a lightning strike in the middle of the day. The off peak readings were complete (I've downloaded the data) but there were no readings during the cut and as a result I was charged as 'Flexible' for the entire day!
I've queried it with Octopus but they have stuck to their interpretation.
This is what I'm trying to get across... it isn't an argument, it's clear in their Terms & Conditions.
This is what I'm concerned about if we have these rolling blackouts.
It could be an absolute mess for Smart Meter owners.
Octopus won't have the resources to start going through everybody's bill... they'll just fall back on their T&C's ... and charge flexi tariff for the whole day...
There is also the very real issue of Smart Meters failing. It's an electronic hardware device being turned on, turned off, turned on, turned off... for days on end. With them all trying to reconnect at the same time... It was never designed for that.