How to access A10S SD/MMC and microSD cards from Android?

[kbro]

I have the A10S with 4GB NAND which Android boots from just fine.  But if I put a SD card in the SD/MMC slot, or a microSD card in the microSD slot, then I can't access them using the build-in file manager - it can't see the device.  I'm guessing the devices are set up for booting rather than hot-swap, so is there a config file I need to change?  A USB memory stick works entirely as expected.