Preserve previously scanned data - problem

[ivanstef]

I installed Y2M , (setup: MED500X with internal HDD 2TB, and external 2TB attached via USB. (all connected via wifi)
Problem appeared when i first tried to transfer movies from internal drive to Y2M (\\mede8er\hdd1\Movies) and the „Preserve previously scanned data“ was checked. After few hours, process finished and on the left side appeared whole list of movies (which is ok, this far?).  (after this step, i didn't start "Run YAMJ to Mede8er!", should i?)
Then i tried to do the same with movies from external drive (\\mede8er\usb1\Movies) ,again with „Preserve previously scanned data“ checked. After the process finished, the list on the left side vanished, and was replaces with list of movies from external drive.
What am i doing wrong?  
And if i solve this problem, should „Process all titles“  and „Overwrite existing films“ be checked..or not?

Could someone help, please?

Snopes
 

[Maasbommel]

I think you should set:
- preserver previous scanned data

And be sure not to have selected:
Delete unused files from the jukebox

That should keep your previous scannned data.