mpsPrefixFields = False breaks primary key configuration "Id <parameters...>"

Stack: LTS-9.21
OS: Ubuntu 14.4
backend: mysql
In the code below. Compilation fails if mpsPrefixFields is set to False. If set to True it succeeds.

share [mkPersist sqlSettings { mpsGenerateLenses = True, mpsPrefixFields = False }, mkMigrate "migrateAll"] [persistLowerCase|

Foo json
  Id sql=REQ_ID
  field1 String
  field2 Int
  deriving Show
|]

 > stack build
 servant-persistent-0.2.0.0: unregistering (local file changes: src/Models.hs)
 servant-persistent-0.2.0.0: build (lib + exe)
 Preprocessing library servant-persistent-0.2.0.0...
 [4 of 6] Compiling Models           ( src/Models.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/Models.o )
 
 /home/someuser/Documents/src/labs/servant-persistent/src/Models.hs:31:1: error: Not in scope: data constructor ‘FooId’
 
 --  While building package servant-persistent-0.2.0.0 using:
       /home/someuser/.stack/setup-exe-cache/x86_64-linux/Cabal-simple_mPHDZzAJ_1.24.2.0_ghc-8.0.2 --builddir=.stack-work/dist/x86_64-linux/Cabal-1.24.2.0 build lib:servant-persistent exe:perservant --ghc-options " -ddump-hi -ddump-to-file"
     Process exited with code: ExitFailure 1

Start with src/Models.hs and reproduce the reported stack build using the shown persistent schema, mysql backend, and mpsPrefixFields = False. Trace the generated primary-key configuration around the reported FooId error and verify that the same schema compiles with the option disabled while retaining sql=REQ_ID.