My first installation of Tunnelblick was after I had already updated to macOS, so I had no update problems or older versions of Tunnelblick laying around.
My Tunnelblick is 3.6.7c (build 4606)
Everything is working great and I'm very impressed with the performance. The only problem I have noticed is that the icon in the menubar becomes unresponsive.
I think this happens after a period of time where the VPN is disconnected and the computer has been asleep. I usually notice when I take the computer out to a coffee shop. The icon (disconnected) appears, but clicking on it has no effect. The status window does not appear and I can't use the icon to connect. Launching the app from the Applications folder works properly, but even after connecting, the icon in the menubar does not change and is still unresponsive to clicking.
Rebooting the computer will make the menubar icon work properly again. But after a while it will become stuck again.
I have tried this with two different versions of the menubar icon and both acted the same way.
Not a big problem because Tunnelblick continues working properly, just a little cosmetic/annoying issue.