I have a very stripped-down desktop environment on Linux (i3wm). Therefore i have some issues with the autostart option. At first, the Autostart-checkbox didn't work for me. I have reached out to the twitter support, and they told me what technique they are using for this option: "A file named Enpass.desktop should be created there at /home/.config/autostart." - this helped me to re-create a custom autostart script like i had with Enpass 5. However, i am missing the startWithTray option. Since the Enpass UI lacks the "Start minimized" option on Linux, and i3wm has no support to start applications minimized on its own, i currently get a full Enpass window on every boot plus a systray icon. I have to manually close the main window to have Enpass properly running "in the background". I am disappointed that there is no more option to start Enpass minimized on the command line. 

OK, there is an undocumented option. Just start Enpass with the "-minimized" flag.