Beginning to think you might be right. Think I should buy my next card from PC World or the CO-OP saw some in there.
OK so after the Donkey Kong game and update successfully copied to the SD card using the WHS 2011 file server instead, I tried to install it again on the Wii U via WUPInstaller.
But still getting the error "Install of title 00000000-00000000 failed. Error: not a game, game update, dlc, demo or version title".
I then put the SD card back into the file server which took several attempts before Windows would even detect the card, looking in the game update folder all the files that were in there are now missing. But the 10.8GB of files for the actual game are all still present though.
Seems to be doing a similar thing to what it was doing on Windows 10 with files vanishing off the SD card. So looks like the SD card is dodgy.
Think I will have to buy another card from a known retailer and try again.
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I will call Sandisk tomorrow as I still have the packaging see what they say about it ? Just emailed the eBay seller as well asking if they are legit LOL.