How current total is caluculated in /bill ?

1.Created account on 19th Oct'18

2. Ran bill on 19th Nov'18 and 19th Dec'18 and both bills have charges as expected

3. Ran bill on 19th Jan'19 (notice change in year though not relevant)

All items are billed properly and have bill_obj_id0 and ar_bill_obj_id0 rightly pointed to 19th Jan'19 bill, but current total in bill object  is 0. I ran bill for next couple of cycles till Apr'19, but still the same result

After analysis, cm.pinlog shows below flist to calculate current total which is returning 0. ( Notice highlighted fields)

D Fri Apr 19 10:10:00 2019  XXXX  cm:25889  fm_bill_make_bill.c:5054 2:XXXX:testnap:25887:-143521120:110:1539989475:1:root.0.0.0.1:::