Maybe not a bug per se, but currently British royal engineers cannot be ordered to vault a damaged sandbag since the default action is repair. This could obviously be problematic if the sandbag blocks off a passage. I don't remember if the issue exists with Sturmpioneers, soviet engineers and conscripts with repair kits (and these factions' corresponding sandbag walls).
In any case, the default action should probably be changed to vaulting, because repair can always be ordered from the control panel.
Added Issue to database. Thanks