New test step does not save correctly

I have been working on a new type of test step - RestTestRequestWithRetryStep, which extends RestTestRequestStep with some basic retry functionality. Everything works well in the client, I can add a new RestTestRequestWithRetryStep and also "add retries" to an existing RestTestRequestStep.

But when I try to save the test, or the entire project, ReadyAPI doesn't save the new steps correctly. Needless to say, when I load the saved project, the new steps are essentially gone. This is what's actually being saved - the new test step doesn't have an ID, nor does it have a config:

...</con:testStep>
<con:testStep type="RestTestRequestWithRetryStep" name="REST Request with Retry"/>
<con:testStep type="restrequest" name="Verify Group with Feature" id="4ac98a7d-b290-4aca-948f-06be471dc4f2">
...

I hope that I'm missing something simple, can someone please help me? Here's some of my code:

@PluginTestStep(typeName = RestTestRequestWithRetryStep.REST_TEST_REQUEST_WITH_RETRY_STEP, name = "REST Request with Retry", description = "REST Test Request with Retry Step")
public class RestTestRequestWithRetryStep extends RestTestRequestStep {

	public static final String REST_TEST_REQUEST_WITH_RETRY_STEP = "RestTestRequestWithRetryStep";
	
	private int maxRetries;
	private int retryInterval;
	private final int DEFAULT_MAX_RETRIES = 3;
	private final int DEFAULT_RETRY_INTERVAL = 5;
	
	public RestTestRequestWithRetryStep(WsdlTestCase testCase, TestStepConfig config, boolean forLoadTest) throws ItemDeletedException {
		super(testCase, new RestRequestWithRetryStepFactory().createNewTestStep(testCase, config.getName()), forLoadTest);
		try {
			setMaxRetries(DEFAULT_MAX_RETRIES);
			setRetryInterval(DEFAULT_RETRY_INTERVAL);
		} catch (InvalidSettingException e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}
	}
    
	@Override
	public TestStepResult run(TestCaseRunner testRunner, TestCaseRunContext testRunContext) {
    	
		int retryCount = 0;
		TestStepResult stepResult = null;
		boolean tryAgain;
    	
		do {
			stepResult = super.run(testRunner, testRunContext);
			tryAgain = false;
			retryCount++;
			if (retryCount <= getMaxRetries() && stepResult.getStatus().equals(TestStepStatus.FAILED)) {
				tryAgain = true;
				try {
					Thread.sleep(getRetryInterval() * 1000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		} while (tryAgain);
		return stepResult;
	}
	@Override
	public void resetConfigOnMove(TestStepConfig config) {
		super.resetConfigOnMove(this.getConfig());
	}

public class RestRequestWithRetryStepFactory extends RestRequestStepFactory
{
	@Override
	public WsdlTestStep buildTestStep(WsdlTestCase testCase, TestStepConfig config, boolean forLoadTest) {
		try {
			return new RestTestRequestWithRetryStep(testCase, config, forLoadTest);
		} catch (ItemDeletedException e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}
	}

	@Override
	public boolean canCreate() {
		return true;
	}

	@Override
	public TestStepConfig createNewTestStep(WsdlTestCase testCase, String name) {
		WsdlTestStep step = testCase.getTestStepByName(name);
		if (step == null) {
			return super.createNewTestStep(testCase, name);
		} else {
			TestStepConfig origConfig = step.getConfig();
			RestRequestStepConfig origRestRequestStepConfig = (RestRequestStepConfig) origConfig.getConfig();
			
			RestRequestStepConfig newRestRequestStepConfig = RestRequestStepConfig.Factory.newInstance();
			newRestRequestStepConfig.setService(origRestRequestStepConfig.getService());
			newRestRequestStepConfig.setResourcePath(origRestRequestStepConfig.getResourcePath());
			newRestRequestStepConfig.setMethodName(origRestRequestStepConfig.getMethodName());
			newRestRequestStepConfig.addNewRestRequest().set(origRestRequestStepConfig.getRestRequest());
			TestStepConfig newConfig = TestStepConfig.Factory.newInstance();
			newConfig.setConfig(newRestRequestStepConfig);
			newConfig.setType(RestTestRequestWithRetryStep.REST_TEST_REQUEST_WITH_RETRY_STEP);
			
			testCase.removeTestStep(step);
			return newConfig;
		}
	}
}

@ActionConfiguration(actionGroup = ActionGroups.REST_TEST_REQUEST_ACTIONS)
public class RestTestRequestStepAddRetriesAction extends AbstractSoapUIAction<RestTestRequestStep> {

	public RestTestRequestStepAddRetriesAction() {
		super("Add Retries", "Action for adding retry functionality to a REST Request test step");
	}

	@Override
	public void perform(RestTestRequestStep step, Object o) {
		TestStepConfig newConfig = TestStepConfig.Factory.newInstance();
		newConfig.setType(RestTestRequestWithRetryStep.REST_TEST_REQUEST_WITH_RETRY_STEP);
		newConfig.setName(step.getName());
		
		WsdlTestCase parentTest = step.getTestCase();
		int stepIndex = parentTest.getIndexOfTestStep(step);
		parentTest.insertTestStep(newConfig, stepIndex);
	}
}