For a configured project with a custom CSS (and probably assets), incremental documentation rebuild ignores changes in static files.

Dokka configured for multiModule project. The configuration contains:

pluginConfiguration<org.jetbrains.dokka.base.DokkaBase, org.jetbrains.dokka.base.DokkaBaseConfiguration> {
//            customAssets = listOf(file("<path to asset>"))
        customStyleSheets = listOf(file("custom.css"))
    }

I perform changes in custom.css file and re-run task dokkaHtmlMultiModule. But Gradle marks the task as UP-TO-DATE.
build clean / --rerun-tasks / changes in build.gradle.kts helps

Installation

• Dokka version: 1.6.10