Apps targeting Android Q – API 29 by default are given a filtered view into external storage. A quick fix for that is to add this code in the AndroidManifest.xml:
<manifest ... >
<!-- This attribute is "false" by default on apps targeting Android Q. -->
<application android:requestLegacyExternalStorage="true" ... >
...
</application>
</manifest>
Read more about it here:
https://developer.android.com/training/data-storage/compatibility