When you set up your phone, you were asked how to deal with the SD card.
Android from version 6 on offers two possibilities:
- Incorporate it into internal storage, which would make it invisible to any outside software.
- Leave it as external storage, leaving it visible to the outside and exchangeable.
If you chose option 1, you don’t have a problem, but the intended behaviour.
If you chose option 2, you have a problem … perhaps try this …