I have my Mi Box formatted with a 256gb SD card running as internal memory ...
This is where the warning comes in place ....
I plugged in a second Flash Drive 32gb ...
And now my internal memory can't be Read for whatever reason the USB drive I plugged in even know I selected use as removable storage it now won't let me mount my SD card that's programmed to internal memory
So now I have to probably format my SD card and start over ...
So you have a USB hub and a SD card reader on one USB and a USB drive on another?
What was the warning dialog? Was it about losing you "internal storage" (might have critical files on it?)?
If you take out the USB drive, does it read the SD card? From the sounds of it, I'm guessing no? Did you restart without the USB drive but with the SD card?