Plugin fails for sub-projects

Gradle: 6.0.1
Kotlin: 1.3.61

I am getting the following failure when attempting to use the plugin against any of the sub-projects:

* What went wrong:
An exception occurred applying plugin request [id: 'org.jetbrains.intellij.inspections', artifact: 'org.jetbrains.intellij.plugins:inspection-plugin:0.3.2']
> Failed to apply plugin [id 'org.jetbrains.intellij.inspections']
> Could not create task ':api:checkInspectionsMain'.
> Could not create task of type 'CheckInspectionsTask'.
> org.gradle.api.reporting.internal.TaskReportContainer.(Ljava/lang/Class;Lorg/gradle/api/Task;)V

Not much detail here but I notice the colon's in the task name ':api:checkInspectionsMain' and wonder if that would cause a problem?

Any idea how I can debug this further?