GHC determine illegal kind for standalone deriving with Deriving via

Happy to release GHC 8.6.1-alpha1! I used it to test new extensions, and then I met below errors:

$ ghci-8.6.0.20180627
GHCi, version 8.6.0.20180627: http://www.haskell.org/ghc/  :? for help
Prelude> :set -XDerivingVia -XStandaloneDeriving
Prelude> newtype FunctorWrapped f a = FunctorWrapped (f a)
Prelude> deriving via f instance Functor f => Functor (FunctorWrapped f)

<interactive>:3:33: error:
    • Expected kind ‘* -> *’, but ‘f’ has kind ‘*’
    • In the first argument of ‘Functor’, namely ‘f’
      In the stand-alone deriving instance for
        ‘Functor f => Functor (FunctorWrapped f)’

<interactive>:3:62: error:
    • Expected kind ‘* -> *’, but ‘f’ has kind ‘*’
    • In the first argument of ‘FunctorWrapped’, namely ‘f’
      In the first argument of ‘Functor’, namely ‘(FunctorWrapped f)’
      In the stand-alone deriving instance for
        ‘Functor f => Functor (FunctorWrapped f)’

However,

newtype FunctorWrapped f a = FunctorWrapped (f a)
    deriving Functor via f

is passed through on GHC 8.6.1-alpha1.

Is this a bug or my misunderstand?

Trac metadata

Trac field	Value
Version
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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