AWS is modeling RDS cost in an obscure way for RDS backup assets
The cost in the bill for RDS backups is attributed to the RDS instance from which it came from .
The platform expects that an asset only carries cost when it is active so if charges are ingested for an asset that is inactive for a specific calendar month, it will not be able to link those charges to the associated asset .
This results in unallocated cost for these line items when using perspectives even if the associated item was active previously and tagged properly.