The problem with expanding SD cards is that the market is full of clone or reject cards and cheap counterfeits. An alarmingly large number of them on the market have brand names on them, but are not from the factory. For a while, the Stratux software was self-expanding the SD card on first boot. Shortly after, complaints came rolling in that the disk was corrupted. After weeks of head scratching (because the developers couldn't get it to fail), someone figured out it was bad SD cards. The card would be labeled internally and externally as 8G (or 16, etc) but actually had less. The software would try to expand past the physical limits and have write failures. So the developers had to remove the auto-expand feature not because of faulty software, but because the market was flooded with faulty SD cards, especially when bought online. I buy mine from WalMart and have never had a problem expanding them. If you're going to buy a pre-flashed SD card, your best bet in my opinion is to buy it from the Stratux store on Amazon.
Google "counterfeit sd cards" for a plethora of hits. Here's an eye-opener:
https://www.eetimes.com/document.asp?doc_id=1326059