The Xiaomi smartphone automatically recognizes and releases SD cards for use, but if the SD card has been ejected, it must be made available again.

Android 10 (MIUI 11.0)
Step 1:  Open the  Settings
Step 2:  Tap on  About phone
Step 3:  Tap on  Storage
Step 4:  Tap on  Mount SD card
Step 5:  Confirm with  Mount
  1. Open the Settings
  2. Tap on About phone
  3. Tap on Storage
  4. Tap on Mount SD card
  5. Confirm with Mount

Xiaomi Instructions