Sandisk dual drive USB type C not working on my IPadPro 2018

The only truly “universal” non-proprietary filesystem formats are all FAT-based. Whilst iPad also supports APFS (which will also work with Mac) this is Apple proprietary - locking you in to the Apple ecosystem and limiting portability between systems.

Good to learn that the problem has been easily resolved through re-formatting to a supported standard.

To be recognised by iPadOS, the attached USB storage device must be formatted to FAT, FAT32, exFAT or APFS+ with a single partition. As the iPad has limited power capabilities, dependent upon the Storage Device, an external power source is often required.

If your iPad Pro has a Lightning port, you will need to use an Apple Lightning to USB3 Camera Adapter to directly connect USB devices to the iPad. This adapter has both a USB 3.0 Type-A connector and an additional Lightning port to supply power, from your charger, to both the iPad and connected device. The external charger must be rated at 12W or more.

If you have one of the newest iPad Pro models, with a USB-C connector, you may need to utilise a powered USB hub (i.e., it has its own source of power) - connecting both the iPad Pro and the storage device to ports on the hub.

I hope this is helpful.

Delighted to help.

You are certainly not the first to discover that the iPad cannot supply sufficient power to operate an external storage device - and you won’t be the last. The iPad is designed to be frugal in its use of power - as such, it’s battery (and ability to power external devices) is quite limited.