IntelliJ Show an Error on kotlinx.serialization, but compiling works - kotlin

Question

I have a problem where IntelliJ tells me that the #Serializable annotation cannot be accessed as it's internal to kotlin.io etc. The kotlinx.serialization package also shows as an unresolved reference.
Apparently, this has something to do with using Kotlin 1.7.x as when I downgrade to Kotlin 1.6.10 the issue no longer presents itself. However, Gradle compiles and runs the application without issue even on 1.7.10. Therefore, this seems like ultimately an issue with IntelliJ and/or one of my settings.
This is a Kotlin Multiplatform project. I've tried many things to fix this:
Reloading Gradle Project
Refreshing Gradle Dependencies
Completely refreshing all project indexes via the new Repair IDE tool
Deleting .idea and .gradle folders
Adjusting the project structure versions
Generally messing around with versions and settings
My build.gradle.kts:
plugins {
application
kotlin("multiplatform") version Versions.kotlin
kotlin("plugin.serialization") version Versions.kotlin
}
group = "com.example"
version = "4.0"
repositories {
mavenCentral()
}
kotlin {
jvm {
compilations.all {
kotlinOptions.jvmTarget = "17"
}
withJava()
testRuns["test"].executionTask.configure {
useJUnitPlatform()
}
}
js {
binaries.executable()
browser {
commonWebpackConfig {
cssSupport.enabled = true
}
webpackTask {
outputFileName = "app.js"
}
}
}
sourceSets {
val commonMain by getting {
dependencies {
implementation("io.ktor:ktor-client-core:${Versions.ktor}")
implementation("io.ktor:ktor-client-websockets:${Versions.ktor}")
implementation("io.ktor:ktor-serialization-kotlinx-json:${Versions.ktor}")
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:${Versions.serialization}")
}
}
val commonTest by getting {
dependencies {
implementation(kotlin("test-common"))
implementation(kotlin("test-annotations-common"))
}
}
val jvmMain by getting {
dependencies {
implementation("io.ktor:ktor-server-core:${Versions.ktor}")
implementation("io.ktor:ktor-server-auth:${Versions.ktor}")
implementation("io.ktor:ktor-serialization:${Versions.ktor}")
implementation("io.ktor:ktor-server-html-builder:${Versions.ktor}")
implementation("io.ktor:ktor-client-cio:${Versions.ktor}")
implementation("io.ktor:ktor-server-cio:${Versions.ktor}")
implementation("io.ktor:ktor-server-websockets:${Versions.ktor}")
}
}
val jvmTest by getting
val jsMain by getting {
dependencies {
implementation("io.ktor:ktor-client-js:${Versions.ktor}")
implementation("io.ktor:ktor-client-json:${Versions.ktor}")
implementation("io.ktor:ktor-client-auth:${Versions.ktor}")
implementation("io.ktor:ktor-client-websockets:${Versions.ktor}")
implementation("io.ktor:ktor-client-serialization:${Versions.ktor}")
implementation("org.jetbrains.kotlin-wrappers:kotlin-react:${Versions.react}")
implementation("org.jetbrains.kotlin-wrappers:kotlin-react-dom:${Versions.react}")
}
}
val jsTest by getting
}
}
application {
mainClass.set("com.example.app.ServerKt")
}
tasks.named<Copy>("jvmProcessResources") {
val jsBrowserDistribution = tasks.named("jsBrowserDistribution")
from(jsBrowserDistribution)
}
tasks.named<JavaExec>("run") {
dependsOn(tasks.named<Jar>("jvmJar"))
classpath(tasks.named<Jar>("jvmJar"))
}
object Versions {
const val ktor = "2.0.3"
const val kotlin = "1.7.10"
const val coroutines = "1.6.3"
const val serialization = "1.3.3"
const val react = "18.2.0-pre.358-compat"
}
The class that is having issues is:
import kotlinx.serialization.Serializable
#Serializable
data class Customer(val id: Int, val firstName: String, val lastName: String)
I appreciate any help I can get