@HMo 

Hi,
If you are away from the camera, please ensure your Tapo app is up to date. Then, try rebooting the camera via the Tapo app and check if you can format the SD card in the Tapo app.

If the same phenomenon persists, you can try the following steps when possible and confirm the relevant information for further analysis.
  1. Power off your camera, remove and reinsert the SD card several times. Then, power the camera back on and check if the phenomenon persists.
  2. Test the SD card in another camera or on a computer with an SD card reader. See if it can be recognized or formatted outside the Tapo system.
  3. Try a different SD card if you have one.
  4. What's the SD card's model number and capacity?
  5. Please test the SD card with third-party software like H2testW, then send us the test results.
      How to Verify Fake Micro SD Cards

Best Regards