INDIRECT Formula used to work but now it isn't..

Hello,

I have a formula that used to work. It would work out the date of a task whether or not it has a dependency on another task or not and act accordingly with INDIRECT. It is below:

=IF($J12="Yes",IF(INDIRECT("O"&I12+9)="","",IF(I12<>"",WORKDAY(INDIRECT("O"&I12+9),1),K12)),IF(INDIRECT("N"&I12+9)="","",IF(I12<>"",WORKDAY(INDIRECT("N"&I12+9),1),K12)))

The problem is that when I12 returns "", M12 (which has this formula) still won't return the date from K12.

This has me scratching my head hard as it was working before and now it is not. Any help would be great, thanks!

Link to the file: