Change to Value Set attached to an OAF form DFF taking time to replicate

We are upgrading from 11i to R12.1.3

We have value sets attached to the Address Information(1) DFF (i.e. DFF on Customer Site).

I am making changes to the Value Set definition, in fact choosing a new Value Set altogether for an attribute for the Customer Site DFF. But the Customer Site form (which is an OAF in R12) is still using the old value set for an unpredictably long time - then on its own it starts using the new Value Set definition.

I am making the change in the same way as I do it in 11i - in Descriptive Flex Field form - unfreezing before making the changes then freezing afterwards allowing the DFF to recompile.