NoSuchFieldError for a private field in a class

Question

I am facing an issue where my android code is throwing NoSuchFieldError only on some Samsung devices. From what I understand, NoSuchFieldError usually occurs due to usage of different library version at compile and run time. However, in this case, why would a private field result in this error? If it helps, I use proguard and this class is used by injection via dagger.

java.lang.NoSuchFieldError: No field mIsRegistered of type Z in class Lcom/my/package/MyClass; or its superclasses (declaration of 'Lcom/my/package/MyClass' appears in base.apk!classes11.dex)
    at Lcom/my/package/MyClass.myMethod(MyClass.java:97)
    at Lcom/my/package/MyClass.myMethod(MyClass1.java:36)

My code basically looks like this:

public class MyClass extends BroadcastReceiver implement MyInterface {

    private final Object mLock = new Object();
    private volatile boolean mIsRegistered = false;

    public MyClass() {
    }

    @Override
    public void myMethod() {
        synchronized (mLock) {
            if (mIsRegistered) {
                // do something
            }
        }
    }
}

My proguard config is similar to:

-keep class com.my.package.** {*;}