Not able to increment the multiple type list variable using MNI

Hi Appian Pals, 
I have a requirement to send a variable which is of type multiple to send it one by one in an incremental way in the sub process.
I tried to achieve this by using MNI in the script task and align the values by using spawn all in the list variable and then align them in the new pv.
Now that pv is not getting the value from the second index. For the first instance, it is getting the value and getting inside the sub process, but for the second value in the list, it is not incrementing and getting updated.

What i want is recursively the list should increment and assign values to the pv so that it can go into the sub process.
Any of the directions would be appreciated.