Saving documents to your SD Card in Scan Pro App for Android:
This may sometimes happen and it depends on your device. Basically Scan Pro App is only saving scans to locations which Android recognizes as external locations. This might or might not be a SD card.
For now you can't do something about it. We could - and we might do in the future - however, this would make the app and the infrastructure much more complex. Let us know if you have further questions in this direction!