Tabbed Custom Data Required Field Submit Values Ignored

Tabbed custom data sets (both single and multi-value) that contain a required field always return that the field is required even with a value submitted, so you can't create or edit the set. Inline custom data sets with a required field work fine.

I'll note that when the form is redisplayed on a validation fail, none of the submitted values, required or not, are redisplayed, so you've got to reenter everything. Not sure if this is related.

I'm still debugging. I'll submit additional details when I have it.