I think this is the correct answer - My free bluelink period ended a couple of months ago and since then I'm on the 'Plus' plan, but Hyundai in their wisdom, have excluded OTA updates from this plan.
So, for the first time, I've gone through the USB update process using the Navigation Updater app and I can confirm that the version that it currently downloads for the Standard Gen5W is NE_E.EUR.S5W_L.001.001.250226 (this is what I was already on).
So, unless I'm doing something wrong, Hyundai haven't made the latest version available for manual update as yet.
Bugger!
Macca