I thought I had replied to this post already, guess I replied to a message or something from someone else... oh well.
I'm not sure about fixing this issue but in the old mouse properties system there was a lot more options which allowed us to define exactly what each button did. The new simple system doesn't seem to allow us to do that.
I believe you can still define it using lua script - not sure though as I've not tried.
GameRightMouseClick
Defines what the right mouse button is used for.
'0' (eIndividualAction): used for individual actions.
'1' (eActivateStandardCommand): activates standard command.
'2' (eActivateNextCommand): activates next command.
'3' (eStandardAction): used for standard action (GameRightClickAction).
'4' (eSandardActionWithIndividual): used for standard action (GameRightClickAction) and individual actions.
game:setValue(VGameRightMouseClick, 0)
or...
game:setValue(VGameRightMouseClick, eIndividualAction) -- I think...