Why can't I use my SD card as internal storage on Android 6.0 Marshmallow?

[AC Question]

I have an Alcatel Pixi 4 7'' with 8GB of internal storage, 1GB RAM and Android 6.0 Marshmallow. My device has no free space left so I figured I'd get an SD card and set it up as internal storage. I did some research on the subject and I bought a 16GB SanDisk SD Card Class 10 UHS-1, which was the recommended kind for using as internal storage. As it turns out I'm not able to set the SD card as internal storage, the process of formatting the SD card gets stuck at 20% and after a while an error message comes up telling me it can't be formatted. After that when I open storage configuration my device either detects the SD card but shows a message that says "checking" ad it won't allow me to do anything with it or it won't detect it at all. I tried checking my SD on my laptop and of the 16GB it's supposed to have it only shows 15MB of storage, but I managed to format it and recover the 16GB of space. I did this using FAT32 and not only with the quick format option. After all this and several failed attempts I still can't get my SD card to work as internal storage, anyone knows how to solve this problem?

 

[chanchan05]

Verify first that you have a legit card and have not been scammed. Download SD Insight and use it.

 

[ACZEpp2303]

I used SD Insight and it says the model: SL16G, size: 16GB, manufactured by SanDisk Corporation. As far as I can tell it isn't fake