Before you go out buying something you may not need I would do the following
1. Put back your old microsd card in your Wiiu and validate that you do in fact see all your apps on your Wiiu.
2. Reformat your new card (it needs to be Fat32) not exFat or NTFS. Note that the regular Windows format option by default doesn't show the option for Fat32 when you have larger cards over 32gb , so you may need to use 'Diskpart" or a 3'rd party tool .. more info here
**Tip** , when you're doing this step, make sure to use the same microsd adapter that you plan on using with the Wiiu
to rule out the adapter as the issue **
3. Copy everything again from Original card to new Card .. Once this is done ( do a Size compare between the 2 cards to validate that everything copied over )
4.With your Wiiu powered off, insert the new MicroSD card (using the same adapter that worked in Step2 above
Over the years, I've never had a microsd card issue with my Wiiu so long as it's properly formatted and you're using a compatible adapter.
With all the respect to the great user @jeannotte
, from my side and experience I confirm what @AQS
says and I add my experience in years as below.
I would love to bring my experience on that, in the past I have tested many SD/MicroSD Kingston, SanDisk, Toshiba and other brands that I don't remember, but I noticed that it's not the problems about the Micro SD with Adapter or the Normal full size SD, the problems was related to the brand it self and some kind of compatibility issue
(per my understanding, probably it's how the SD it manage the datas in background with the electricity efficiency on that) and doesn't matter if it's old SD or the newest fastest MicroSD/SD.
Example, on my old Wii (i navigate and asked to the Forums, and I read many opinion in the past, which SD it's better) this compatibility I tested many times with new different - and same specs in the time - SD/MicroSD formatted in FAT32 32kb Cluster (if I don't remember bad) this because in Wii it's even more important which Cluster allocation on formatting stage you are using.
So, I noticed that when I transferred the same datas in different SD brands it let works the Homebrew apps in different way (like speed issue or corruption data and so on), and I remember the Kingston in front of SanDisk can last a bit better because SanDisk has the tendency to corrupt the Datas after certain of usage but the SD apparently perform fine (before I was thinking that SanDisk was the best, maybe was) but in time I continued to do the test and I arrived to the point that Samsung MicroSD/SD cards are the best.
Probably the Corruption sometimes, it's related to too much fragmented structure form the SD ; so better to erase it and fill the SD with the 0 byte because the SD working better as the files are one next to each other instead of to let it to copy structure file randomly. And another thing that corrupt the SD, even if you don't transfer for so many times the files into it, it's the Turn OFF Console Stage. On the Console Turn OFF stage, the SD receive kind of a small shock of electricity and this influence the operation of it, and on Samsung I found really solid in the time for this.
So, first of all, follow what the other user says above just test and second share the Micro SD card that you bought , to understand better if it's solid good quality MicroSD. Or what so ever......