exp-00008, ora-00604, ora-01426 with direct=y on 12c

Env: 12c (12.1.0.2) on Solaris x86

Problem: while taking an export dump using the old exp utility, encountered foll. errors with direct=y:

EXP-00008: ORACLE error 604 encountered

ORA-00604: error occurred at recursive SQL level 1

ORA-01426: numeric overflow

However, it works fine without direct=y.

Can anybody help find what could be the reason?

We have another server with identical env. and it works fine with direct=y.

Couldnt find any bugs on MOS. And though we can still use traditional exp/imp but we cant raise a defect.

Thanks