Work Offline button vanishes at startup and editor gets stuck waiting

When trying to load Unity without an internet connection the "Work Offline" button dialog vanishes and leaves a white "Loading" panel with a thin blue loading bar along the top. Nothing ends up happening though, it just sits there waiting with nothing to click on except the top bar "X" to close. The only way to get it working again is to get an internet connection.

This is happening with the 2017.x and 2018.x editor builds. I get this issue every day when trying to open Unity on my morning commute to work. If you were quick enough (less than 1 second on my machine) you used to be able to click the "Work Offline" button before it vanishes. With newer editor builds this is no longer possible, the startup times must be getting quicker. Using the "Load Previous Project on Start" feature seems to not be affected by this issue, but it is not always desirable to load the previous project when you have a couple of projects.

Trying to reproduce this by exiting Unity and disconnecting internet, then starting Unity again, always seems to show the project selection dialog just fine. It only seems to happen after some longer period of time between closing and opening Unity. I've had it happen 5 minutes after closing Unity.

My machine is running Ubuntu 18.04 (Gnome 3.28.1, X11 desktop session).

 

It was something that was fixed a while ago but sadly has reappeared recently. Frustrating when you work on a train