Circuit breaker state fluctuates until stably open

Question

I set the following properties:

HystrixCommandProperties.Setter commandProperties = 
HystrixCommandProperties.Setter();
commandProperties.withCircuitBreakerSleepWindowInMilliseconds(20000);
commandProperties.withMetricsRollingStatisticalWindowInMilliseconds(30000);
commandProperties.withCircuitBreakerErrorThresholdPercentage(40);
commandProperties.withCircuitBreakerRequestVolumeThreshold(10);

HystrixCommand.Setter config = HystrixCommand
            .Setter
            .withGroupKey(HystrixCommandGroupKey.Factory.asKey("KEY"));
config.andCommandPropertiesDefaults(commandProperties);

It's being observed on the hystrix dashboard that the circuit fluctuates between open and close for a couple of seconds before stabilizing into the open state and then follows the sleep window. My understanding is that after being open the first time around, all requests should go to fallback and circuit should remain open until the sleep window passes after which it should check and reinstate the respective state. The fluctuation between open and close isn't complying by my understanding.