this is the iXpand USB 3.0 board. Do you have an iXpand UBS 2 or iXpand USB 3?
iXpand USB 3.0
http://kb.sandisk.com/app/answers/detail/a_id/18644/
iXpand USB 2.0
http://kb.sandisk.com/app/answers/detail/a_id/16286/
If you have the 2.0 and you are running FW 4.4.9 (the latest release) it should work with iOS 9.3.5. Was the drive working priviously? Does it work on other iOS devices?
If it worked previously and if it is not working on other iOS devices it seems like it may be defective and would need to be replaced. If that is the case contact sandisk support and ask about warranty replacement.
