Scala 2.11 refined with scalatest MustMatchers and Await causes compiler error "trying to do lub/glb of typevar ?F[?T, ?B]" - scalatest

Question

I have been trying to use the refined with scalatest and am getting compiler errors at the "typer" phase: trying to do lub/glb of typevar ?F[?T, ?B]
This is my best attempt at a minimalist reproduction of the issue using a self-contained ammonite script:
import $ivy.`eu.timepit::refined:0.9.0`
import $ivy.`org.scalatestplus.play::scalatestplus-play:3.1.2`
import org.scalatest.{MustMatchers, WordSpec}
import scala.concurrent.duration._
import scala.concurrent.{Await, Future}
import eu.timepit.refined.auto.autoInfer
class RefinedSpec extends WordSpec with MustMatchers {
val duration = 500.millis
val fut = Future.successful("123")
Await.result(fut, atMost = duration)
}
If you make any one of the following changes to the above it will successfully compile:
delete: import eu.timepit.refined.auto.autoInfer
remove: with MustMatchers from the class definition
delete: Await.result(fut, atMost = duration)
To clarify, this is a compilation error, not a runtime error. The original error is happening in a play app (scala 2.11.11) whilst running test:compile in sbt, but it's probably easier to reproduce it with the ammonite script.
The ammonite version I'm using gives version info:
Welcome to the Ammonite Repl 1.1.2
(Scala 2.11.12 Java 1.8.0_25)
Installed using:
sudo sh -c '(echo "#!/usr/bin/env sh" && curl -L https://github.com/lihaoyi/Ammonite/releases/download/1.1.2/2.11-1.1.2) > /usr/local/bin/amm && chmod +x /usr/local/bin/amm' && amm
More error details from the ammonite example:
scala.reflect.internal.FatalError:
trying to do lub/glb of typevar ?F[?T, ?B]
while compiling: fail.sc
during phase: typer
library version: version 2.11.12
compiler version: version 2.11.12
reconstructed args: -nowarn -Yresolve-term-conflict:object
last tree to typer: Ident(<argument>)
tree position: line 15 of fail.sc
tree tpe: String
symbol: <none>
symbol definition: <none> (a NoSymbol)
symbol package: <none>
symbol owners:
call site: class RefinedSpec in object fail in package $file
From play sbt test:compile I also get this kind of output:
[error] last tree to typer: Ident(<argument>)
[error] tree position: line 13 of ...../RefinedSpec.scala
[error] tree tpe: String
[error] symbol: <none>
[error] symbol definition: <none> (a NoSymbol)
[error] symbol package: <none>
[error] symbol owners:
[error] call site: class RefinedSpec in package foo in package foo
[error]
[error] == Source file context for tree position ==
[error]
[error] 10 val duration = 500.millis
[error] 11 val fut = Future.successful("123")
[error] 12 Await.result(fut, atMost = duration)
[error] 13 }
This isn't a serious issue as I can just remove the autoInfer import as I'm not actually using it. It will trip people up though because they'll tend to do:
import eu.timepit.refined.auto._
to get automatic conversion from compile-time constants into refined types, when they can probably just get away with:
import eu.timepit.refined.auto.autoRefineV