The answer to this will depend on how many legs were included in the multi and how many were voided. For a bonus bet to be awarded, your multi needs to have a minimum of two winning legs.
This means that, if you placed a 3 leg multi where 1 leg is void and 1 leg has lost, you will not get a bonus bet in return unfortunately. In this case, the token will not re-credit to your account.
However, if you placed a 4 leg multi where one leg is void and 2 out of the remaining 3 legs win, you will get a bonus bet return (as the minimum winning legs was achieved).