Praise be to Allah the Lord of the Worlds.
Hajj-Mabrur is the Hajj that Allah accepts and assigns a great reward for, as evidenced by the saying of the Messenger: "There is no reward for Hajj Mabrur except Paradise."{Bukhari & Muslim}.
According to the most preponderant opinion of scholars, Hajj-Mabrur is the Hajj that is free of sins, acts of disobedience, Riya`(show-off in the sense of desire that others witness one`s good acts.), forbidden acts, violating the restrictions of Ihram, backbiting and the like. An-Nawawi says, "According to the more correct widespread opinion of our scholars, Shafie, Hajj-Mabrur is the Hajj that doesn`t involve sin. The word Mabrur is derived from the word Birr, which is obedience. It is also the accepted Hajj and one of the signs of this acceptance is that the pilgrim turns into a better person by not going back to sin. It is also said that Mabrur is the Hajj free of Riya` and not followed by sin.
"There is no reward for it except Paradise." This statement indicates that the reward for the performer of Hajj-Mabrur isn`t limited to expiating some sins; rather, he/she is bound to enter Paradise. Kindly check the book [Shareh Muslim, vol.9/pp.118-119.]
Since Hajj is an obligation once in a lifetime, a pilgrim should be keen on performing all its pillars, obligatory acts, in addition to voluntary and recommended acts of Sunnah that complete his/her reward.
In conclusion, leaving out a voluntary or a recommended act of Sunnah during Hajj doesn`t remove a pilgrim`s reward for Hajj-Mabrur Insha`Allah. However, the pilgrim who performs all of these acts receives the complete reward. And Allah The Almighty Knows Best.