Hello, I believe this issue began when I installed version 3.4.1 Beta 5. I saw that Beta 6 had something about fixing IE9 tabs disappearing on middle mouse click, so I installed that Beta version but the problem persisted in the mentioned programs. Unmaximizing, and remaximizing the program brought the bars back.

I have since reverted to version 3.4.0 and the problem has gone away. The issue only occurred when I closed the tabs with the middle mouse click, right clicking the tabs and choosing 'Close Tab' closed the tab normally without any issues, so did a keyboard shortcut.

Confirmed, Beta 7 addresses these issues. Thanks for the fast turnaround guys. You rock