I just bought this Galaxy tab from Sam's club. It's the a9+ it does not come with a memory card but it says it can hold up to 1 TB. So I bought a 512 GB card brand new and inserted it just as the instructions say. But the tablet will not detect that There is a card inserted. I have one of those multi multi card and USB readers and I inserted it in the bottom of the tablet in the charging port and it will detect it through that. But the little slot/ tray that holds the microSD card does not recognize a card has been inserted. I took the SD card out of my old tablet and tried to insert it and it didn't recognize that either.
If you are within the return window at Sam's I'd bring it back and exchange it. Sounds like it's a defective reader. I assume you have restarted the tablet with the card inserted and also made sure you have the card installed correctly.
The A9 plus is a budget tablet that does not have the horsepower to run many of the new super fast memory cards. I am willing to bet this is the case. Are both of the ones you tried in your tablet those new super fast memory cards? If so, do you have an older memory card to try?
