GSON is only available on JVM or Android targets, so it sounds like Gradle is failing trying to fetch that dependency for another MPP target. In that case, the whole Gradle build will fail, and IntelliJ won’t know anything about your project structure if Gradle fails while doing a Gradle sync.
In these kinds of situations, IntelliJ might not be able to give you the best diagnostic info, but if you run any Gradle task from the command line, you should be able to see the errors