Memory cards are automatically recognized by the Huawei smartphone and released for use. If the memory card was unmounted, however, it must be made available again.

Android 10 (EMUI 10.0)
Step 1:  Open the  settings
Step 2:  Tap on  Storage
Step 3:  Tap on  Memory card
Step 4:  Tap on  Mount
  1. Open the settings
  2. Tap on Storage
  3. Tap on Memory card
  4. Tap on Mount

Huawei Instructions