After upgrading to the latest version 6.0.0 (149) and change language from French to English before creating a backup from Enpass 5.6.9, all works fine. I've exactly the same number of item in each Enpass.
I've tried to import an Enpass 5.6.9 backup file in Enpass 6.00 (72). Some items are missing after restore.
I've 515 items in Enpass 5 and 492 in Enpass 6 after restore.
Thanks for help.