Petition Cannot Save Extended Attribute

Enrollment flows with extended attributes are failing to save. The data looks OK, and no validation errors are reported, but saveAll fails.

Array
(
[EnrolleeCoPersonRole] => Array
(
[cou_id] => 1
[title] =>
[affiliation] => F
[valid_from] =>
[valid_through] => 2012-08-25
[status] => PA
[co_person_id] => 93
)

[Co2PersonExtendedAttribute] => Array
(
[fte] => 50
)

)