Combining more than 1 path in a scan does not work

I recently tried to run a scan on more than 1 path, with a single json and single csv output, using relative paths, and although I encountered no error message, the output files contained no scan data. ScanCode was setup correctly: cleaned, configured and activated. Running on Ubuntu 16.04.1 LTS. Structure of the command (no flags):

```
/some/directory$ scancode subfolder01/aaa/ subfolder02/bbb/ --json output.json --csv output.csv
```

Running these one at a time worked fine.