I’m an AOE1 ROR veteran and the right click is always working “properly” (to me) that my units always follow my command to attack the target and ignore everything else, even if they are stuck. Since there is no patrol in AOE1, in normal combat we always target multiple units, and have to choose the target wisely so the unit get the best attacking angle.
So I haven’t noticed this is a thing in AOE2 (according to @OwnAirplane3203). As @ShadowKhaash said I likely will be surprised and open a bug report if I command my paladins to attack the king, but they go attacking the halb in front.