"not found" error when a closure on right side of binding uses `val`

[toby5box]

I had a compilation issue in production code today that I couldn't explain, so I reduced it to a minimal case:

import cats.effect.IO

object DeleteMe {
  // I am using this - see: https://github.com/oleg-py/better-monadic-for
  // addCompilerPlugin("com.olegpy" %% "better-monadic-for" % "0.3.1")

  def test_OK = {
    for {
      (a,b,c) <- IO.pure( (1,2,3) )
    } yield a+b+c
  }

  def test_bad = {
    for {
      (a, b, c) <- IO.pure(11).map{ _ =>
        val g = 3     // <--- Any binding here causes compile to fail
        (1,2,3)
      }
    } yield a + b + c   // compiler says 'not found' for each of these
  }

}

Not sure if I am missing something, but adding that val binding causes the compile to fail, e.g.

[error] /x/DeleteMe.scala:21:13: not found: value a
[error]     } yield a + b + c   // compiler says 'not found' for each of these
[error]             ^
[error] /x/DeleteMe.scala:21:17: not found: value b
[error]     } yield a + b + c   // compiler says 'not found' for each of these
[error]                 ^
[error] /x/DeleteMe.scala:21:21: not found: value c
[error]     } yield a + b + c   // compiler says 'not found' for each of these
[error]                     ^
[error] three errors found