Versioned Settings in Kotlin format throws NullPointerException

Our TC version: TeamCity Enterprise 2018.1 (build 58245)

We turned on Versioned Settings with the following parameters:
Settings format: Kotlin
Generate portable DSL scripts: yes

TC creates an initial commit in the repository (we use git) successfully, but then when it tries to load it back, it throws NullPointerException.
It doesn't like the following line in our Kotlin configuration:

text("project.build.requested_windows_machine", "${Start.depParamRefs["project.build.requested_windows_machine"]}", display = ParameterDisplay.HIDDEN, allowEmpty = true)

More specifically it doesn't like: "${Start.depParamRefs["project.build.requested_windows_machine"]}"

The line is inside:

object SuperProjectLinux : Template({
name = "SuperProject_Linux"

params {
text("project.build.requested_windows_machine", "${Start.depParamRefs["project.build.requested_windows_machine"]}", display = ParameterDisplay.HIDDEN, allowEmpty = true)

Start is defined in the separate file as:

object Start : BuildType({
templates(SuperProjectLinux)
name = "start"
description = "Generate build identifiers"

params {
  param("project.build.requested_windows_machine", "")

Is this some limitation or bug in TeamCity?  Just to mention: we don't modify a generated configuration, i.e. TC can't load a configuration that is generated by it.