BIll now bill has zero due, but its items has charges

Note: This issue is on pvt enabled environment w.r.t bill now

Steps:

When system date is 7th Jan and pvt is 30th Mar. 

2. Create parent and non-paying child accounts on 30th Mar(pvt) with DOM as 1 with an MRC of 100$ on child account

2. Move pvt to 31st March

3. Run bill now on Mar 31st

4. Bill now got generated but total is 0, looks like prune logic in billing to get bill items is based on item creation date

Issues observed from logs is: created_t of items is  on 7th Jan (current date) , but bill now logic is somehow checking for items created later than 28th Jan through 3rd Apr(not sure how these dates are derived)  hence, though items got billed, due of bill now bill is displayed as 0. But the items are linked to correct bill_obj_id0 and drilling down to customer center on the bill also shows correct charges.