are the files stored locally on the phone or are they on the cloud?
when you open the native camera app and choose Albums, do you see All pictures or Camera roll?
Are the pictures normal pictures taken on the iPad or are they from other source or have they been edited in anyway?
You can also contact sandisk support and send them the debug logs. If you go to view files and pull down on the screen a search box will appear. IN the latest iXpand drive app 4.0.0 search sandisklogs. This will open your default email client with the log attached. Attach that log to your support request.
