Rather than enter zero, are you able to delete the entry (the delete key on the keyboard) and pass Review?
Instructions for IRS form 1099-R, page 15, states:
Box 9a
Your Percentage of Total Distribution
If this is a total distribution and it is made to more than one person, enter the percentage received by the person whose name appears on Form 1099-R. You need not complete this box for any IRA distributions or for a direct rollover.