I'm able to reproduce the following with a freshly cloned Propellor:

> stack build
propellor-5.3.5: build (lib + exe)
Preprocessing library propellor-5.3.5...
[ 43 of 171] Compiling Propellor.Types  ( src/Propellor/Types.hs, .stack-work/dist/x86_64-linux-nopie/Cabal-1.24.2.0/build/Propellor/Types.o )

/home/jayess/code/propellor/src/Propellor/Types.hs:251:37: error:
    • Could not deduce (Monoid (Property setupmetatypes))
        arising from a use of ‘<>’
      from the context: (Sem.Semigroup (Property setupmetatypes),
                         Sem.Semigroup (Property undometatypes))
        bound by the instance declaration
        at src/Propellor/Types.hs:(245,9)-(248,74)
    • In the first argument of ‘RevertableProperty’, namely
        ‘(s1 <> s2)’
      In the expression: RevertableProperty (s1 <> s2) (u2 <> u1)
      In an equation for ‘<>’:
          (RevertableProperty s1 u1) <> (RevertableProperty s2 u2)
            = RevertableProperty (s1 <> s2) (u2 <> u1)

/home/jayess/code/propellor/src/Propellor/Types.hs:251:48: error:
    • Could not deduce (Monoid (Property undometatypes))
        arising from a use of ‘<>’
      from the context: (Sem.Semigroup (Property setupmetatypes),
                         Sem.Semigroup (Property undometatypes))
        bound by the instance declaration
        at src/Propellor/Types.hs:(245,9)-(248,74)
    • In the second argument of ‘RevertableProperty’, namely
        ‘(u2 <> u1)’
      In the expression: RevertableProperty (s1 <> s2) (u2 <> u1)
      In an equation for ‘<>’:
          (RevertableProperty s1 u1) <> (RevertableProperty s2 u2)
            = RevertableProperty (s1 <> s2) (u2 <> u1)

--  While building package propellor-5.3.5 using:
      /home/jayess/.stack/setup-exe-cache/x86_64-linux-nopie/Cabal-simple_mPHDZzAJ_1.24.2.0_ghc-8.0.2 --builddir=.stack-work/dist/x86_64-linux-nopie/Cabal-1.24.2.0 build lib:propellor exe:propellor exe:propellor-config --ghc-options " -ddump-hi -ddump-to-file"
    Process exited with code: ExitFailure 1