Using sbt run on simple tutorial example does not execute - scala

Question

On a Windows machine, I am running through the getting started tutorial here: https://www.scala-sbt.org/1.x/docs/sbt-by-example.html
I am able to start the sbt shell and compile but using the run command just hangs and I am forced to Ctrl-C to exit sbt.
Running scala against the JAR file directly also works as expected.
Sample output is the following:
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=256m; support was removed in 8.0
[info] Loading project definition from S:\foo-build\project
[info] Loading settings for project foo-build from build.sbt ...
[info] Set current project to foo-build (in build file:/S:/foo-build/)
[info] sbt server started at local:sbt-server-8c6933abcb6848dbd242
sbt:foo-build> about
[info] This is sbt 1.2.8
[info] The current project is ProjectRef(uri("file:/S:/foo-build/"), "foo-build") 0.1.0-SNAPSHOT
[info] The current project is built against Scala 2.12.7
[info] Available Plugins
[info] - sbt.ScriptedPlugin
[info] - sbt.plugins.CorePlugin
[info] - sbt.plugins.Giter8TemplatePlugin
[info] - sbt.plugins.IvyPlugin
[info] - sbt.plugins.JUnitXmlReportPlugin
[info] - sbt.plugins.JvmPlugin
[info] - sbt.plugins.SbtPlugin
[info] sbt, sbt plugins, and build definitions are using Scala 2.12.7
sbt:foo-build> compile
[success] Total time: 0 s, completed Feb 7, 2019 4:40:45 PM
sbt:foo-build> run
Terminate batch job (Y/N)? Y

Answer 1

This is enough of an answer for my own purposes.
I was able work around this issue by adding a line to my build.sbt file. After adding ThisBuild / scalaVersion := "2.12.8" I was able to use the run command. Following the tutorial linked in the main question I would not expect to have to do this but perhaps someone could shed some light.