Clicking "Check work", produces "Oh no! There was a communication problem." repeatedly. What to do?

Unsure why the is happening. I've never had this particular issue with the code challenges before. My internet connection's good. So far as I can tell, I'm not doing anything unusual compared to other code challenges I've done. Basically, I just click Check Work and it hangs for a bit and then tells me there's a communication problem. This problem has persisted through a full restart of my computer. It seems to be indifferent as to whether I've modified any code or not. I tried checking work immediately after opening up the challenge and after I'd made the necessary modifications for the given task. As such, I'm not sure attaching my code will do any good as it hasn't even allowed me to see what errors my code has. It just tells me there's a communication error and at this point, I'm just curious what troubleshooting step might be worth trying now.

public class ReflectionUtils {
  // Task 1
  public static Method[] getMethods(Class<?> clazz) {
    return null;
  }

  // Task 2
  public static String getModifierString(Method method) {
    return null;  
  }
}