They were Sandisk. One was 2gb the other was 8gb and my dad tried a couple of 16gb before handing the tablet over to me. I formatted BOTH the 2gb and 8gb on tablet, phone, and then finally computer. Both SD cards work in my android phone.. As you can see in the picture the tablet knows it is there, but doesn't at the same time. Because it is "mounted" but no memory available. The tablet I believe can use up to 32gb external.
Potential hardware fault with the SD card reader. The contacts are either damaged or dirty, allowing the reader to still detect the presence of the card but nothing else. If dirty, some contact cleaner will fix that up. Otherwise, the slot needs to be replaced.