What is your android Version, zossebart ?
I tried and saw the display like you described.
After selecting a folder on external SD card, though, the settings overview showed the /storage/<number ...>/...
But back to the path you are using: if you have Android 4.x, this /storage/sdcard1/Locus/data path cannot work, but you nned to use the one Menion mentioned /storage/sdcard1/Android/data/menion.android.locus.pro/srtm.
Android restriction, not Locus.