There is an issue with unloading from UAL to the new Object Storage shed included with patch 1.9.
UAL cannot unload to the trigger because it sees the area as blocked.

If you don't mind editing your game files, you can fix this by changing collisionMask="3149824" for the objectStorage trigger in the objectStorage.i3d to collisionMask="19922944"

I have reported to GIANTS and hopefully the fix will be included in the next game patch, but otherwise I will have to implement a workaround in UAL.