okhttp3 .addHeader Parameter specified as non-null is null

Question

A few users are experiencing constant app crashes since they updated to Android 12. Issue doesn't happen on any of my or my friends devices (also Android 12) so I can't figure out how to fix it. I don't pass a null value here so I'm not sure what is causing the crash. AccessToken is never null or if it would ever be null, value would be "Bearer null". I tried adding null checks, extra logs to get more info, I'm really out of ideas. Does anyone know how I can identify what's causing the problem or if there are any issues in the code below ?

stack trace from firebase

Fatal Exception: java.lang.NullPointerException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkNotNullParameter, parameter value
       at okhttp3.Request$Builder.addHeader(:7)
       at uk.co.evezy.driver.network.interceptors.RequestInterceptor.intercept(RequestInterceptor.kt:33)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.kt:34)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.kt:95)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.kt:83)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.kt:76)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at uk.co.evezy.driver.network.interceptors.NetworkConnectionInterceptor.intercept(NetworkConnectionInterceptor.kt:31)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at uk.co.evezy.driver.network.interceptors.UserAgentInterceptor.intercept(UserAgentInterceptor.kt:47)
       at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
       at okhttp3.internal.connection.RealCall.getResponseWithInterceptorChain$okhttp(RealCall.kt:201)
       at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:517)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
       at java.lang.Thread.run(Thread.java:920)

Interceptor I'm using

class RequestInterceptor @Inject constructor(private val userDataManager: UserDataManager, private val refreshTokenService: RefreshTokenService) : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response {

        var accessToken = ""

        if (userDataManager.getUserAccessData() != null) {
            accessToken = "Bearer ${userDataManager.getAuthToken()}"

            if (userDataManager.isAuthTokenExpired()) {
                accessToken = ""
                runBlocking {
                    accessToken = "Bearer ${refreshTokenService.getNewTokenUsingRefreshToken()}"
                }
            }
        }

        val original = chain.request()
        val builder = original.newBuilder()
            .method(original.method, original.body)
            .addHeader("Authorization", accessToken)
        val newRequest = builder.build()

        return chain.proceed(newRequest)
    }
}

The other 2 interceptors just in case

class UserAgentInterceptor @Inject constructor() : Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response {
            val original = chain.request()

            Timber.d("UserAgentInterceptor: ${chain.request()}")

            val newUserAgent = String.format(
                Locale...,
                "%s %s(%s) (Android %s;  Model: %s;  Brand: %s;  Device: %s; %s)",
                "appName",
                BuildConfig.VERSION_NAME,
                BuildConfig.VERSION_CODE,
                Build.VERSION.RELEASE,
                Build.MODEL,
                Build.BRAND,
                Build.DEVICE,
                Locale.getDefault().language
            )

            val builder = original.newBuilder()
                .header("User-Agent", newUserAgent)
                .method(original.method, original.body)
            val newRequest = builder.build()

            return chain.proceed(newRequest)
    }
}

class NetworkConnectionInterceptor @Inject constructor(private val application: Application) :
    Interceptor {

    override fun intercept(chain: Interceptor.Chain): Response {

            Timber.d("NetworkConnectionInterceptor: ${chain.request()}")

            val request = chain.request()
            val response = chain.proceed(request)

            if (!isInternetAvailable()) {
                throw NoInternetException("No active internet connection")
            }

            return response
    }
    (...)
    }