Unable to extend or retract launch bar [shift+U] at any time on any aircraft.
It should do both if the aircraft was built (designed) to use it.
Shift Key + U Key extend or retract launch bar
Check the read-me that came with the download.
From experience I have found that some keys lock certain commands and until you hit that key what you want won't work.
Odd I know but hit every key on your keyboard including the "F" keys and see if that helps...I know that a weird suggestion but like Widows rebooting can cure all.