Sandisk SSD not working with iPad mini or iPhone 11 Pro Max but works with iPad Pro

I am trying to port some personal movies to a Sandisk 2TB SSD. I'd like to be able to access them via the Files App on my ios devices. However, I have found an issue between my various devices. I am utilizing the Lightning to USB 3 Camera Adapter that I have seen referenced in other postings to provide the additional power to the SSD. The setup works fine on my iPad Pro (12.9" First Gen) but not on my iPad Mini 4 or my iPhone 11 Pro Max. The adapter information on Apple's website states support for all of my devices. I have called Apple Support and even gone to the Genius Bar at an Apple Store (where they sent me home to call Apple Support again and talk to a hardware person instead of the frontline support staff). If anyone has any ideas if there is a one-size fits all solution for connecting my SSD to my ios devices, I'd appreciate any input.