Thanks very much indeed for bringing this to our attention, David.
I run a Microsoft Lumia phone for everyday use and carry along an older Apple phone just to occasionally monitor my Victron SmartSolar 100/20 charger via Bluetooth. This means that I'm not too familiar with Apple products or their App store.
I'm in Andalucia at the moment and did as the Victron video you provided suggested. The app didn't offer any updates. I then updated the Victron app via the Apple store and retried. Bingo! An update from v1.30 to v1.37 was offered and installed without problem.
So if anyone out there is seeking to update their Victron SmartSolar controller I'd strongly advise updating their Victron app before starting the process.
I hope this helps.
Colin ???