Queston:

After updating my phone's software to Android 11 (also known as R OS), I can't use my micro SD card when I'm using apps like Knox Workspace, Dual Messenger, or if I'm selecting multiple users on my tablet. What's going on?

Answer:

Starting from Android 11 (R OS), external memory (like a micro SD card) can only be accessed by the person who put it into the device. So if you've got multiple users set up on your tablet, or you're using an app like Knox Workspace or Dual Messenger, and the current user doesn't match the one who inserted the external memory, then everyone else gets blocked from accessing it.

Just think of it like this - it's kind of like how you can only play with the toys you brought to the playground, and not with someone else's toys.