Strange behaviour when implicit Macro used

Question
1

Hi folks,
I have strange behavior with implicit macro.
When I use it on type defined inside object - works fine (generated Transformer instance is correct).
Example:

class TransformerSpec extends  WordSpecLike {
....
      "parse to instance of case class defined inside module" in {
        import TypeHolder.Point
        val cfg = ConfigFactory.parseString("""point = {x = 1, y= 2}""")
        val tr = implicitly[Transformer[Point]]

        val pl = tr("point", cfg)
        val pr = Point(x = 1, y = 2)
        assert(pl == pr)
      }

In this case Point is defined in separate object:

object  TypeHolder {
  case class Point(x:Int, y:Int)
}

But when I use inheritance like this:

trait  TypeHolder {
  case class Point(x:Int, y:Int)
}
class TransformerSpec extends  WordSpecLike with TypeHolder {
....

the same (just import) code finish with compilation error:

[info] Compiling 1 Scala source to /data/work/akkamo/akkamo/akkamoConfigMacro/target/scala-2.12/test-classes…
[error] /data/work/akkamo/akkamo/akkamoConfigMacro/src/test/scala/eu/akkamo/m/config/TransformerSpec.scala:64: type mismatch;
[error] found : TypeHolder.this.Point
[error] required: TransformerSpec.this.Point
[error] val tr = implicitly[Transformer[Point]]

Generated macro code:

{
  final class $anon extends eu.akkamo.m.config.TransformerGenerator.AT[TransformerSpec.this.Point] {
    def <init>() = {

looks fine. (Remark: trait AT[T] extends Transformer[T] )
I use Scala 2.12.2.
Whole example is located here: akkamoConfigMacro

Any advice? It looks like a bug in the compiler, but I hope the problem is in my code - of course.

thanks for any advice
Juraj