Despite testing this issue throughout the day we've now discovered, thanks to prompts from readers who've encountered the issue with some videos on 3DS systems, that this issue is caused by a restriction to accessing 18-rated content before a specific time. A test after 11pm UK time brought us the download page for ZombiU without an issue, suggesting that Nintendo is restricting the ability to download these games to specific — and very late — hours.
This restriction evidently disregards the submitted age on the Nintendo Network ID or the lack of parental controls activated on the system.
Earlier today we became aware of an issue on the European Wii U eShop that was preventing the purchase of either ZombiU or Assassin's Creed III. It seems to be a problem caused by their classification as 18-rated titles, with the following message being displayed:
You cannot view this content.
The times during which this content can be viewed have been restricted.
Multiple members of the Nintendo Life team have checked this and encountered the same error message throughout today, which means that no fix has been forthcoming following the most recent system update. Our systems don't have any parental controls so the issue remains a mystery - especially as it only affects games rated PEGI 18, not those rated 16.
Have any of you encountered this error? Let us know in the comments below, and we'll endeavour to get details of a potential solution.