Why does numeric overflow occur after SP 7 upgrade to SP 10?

I migrated from HANA SP 7 to SP 10 and began receiving the following error when running queries:

[314]: numeric overflow: search table error: [6944] AttributeEngine: overflow in numeric calculation; fixed8_18 …

The error was mitigated by casting aggregated data to big integer format (i.e. using TO_BIGINT). However, this error did not occur prior to the upgrade.

What has changed in the SP 10 revisions to generate this error?

-KS