Hi Vivek,
This sounds like a bug related to daily invoicing scenarios.
Subscriptions that have a monthly billing cycle can be aligned with the account BCD such that one invoice can contain the charges from multiple subscriptions. Account billing cycles only support monthly cycles and once set, typically by the first subscription created against that account can not be changed.
In your case the invoicing cycle is daily which by default means that each subscription bundle would have its own separate invoicing cycle. If you are adding on extra subscriptions to the parent bundle the billing alignment rules specify whether the child subscription is aligned with the parent bundle to be included on the same invoice or whether it has its own billing cycle and invoice.
Rgs
Shaun