Rekordbox 6 database on external HD

Hi,
I've been using Rekordbox for a while and with version 5 i used 2 computers and database always stored on an external HD. Never had issues until now.
I just installed RB6 and after several days exporting my whole database (almost 50.000) to new version and the new analysis, it worked perfect on 1 computer, then I tried and plugged the HD on the other computer and as soon as the app starts it says I need to export and analyze the database (again?).

I went back to the other computer to check the database was ok, and it opens perfectly without asking to analyze and export again. Any ideas how can I solve this without analyzing and exporting again in the other computer? it should be working perfect as it runs from external HD.

Hope it's clear.
Thanks