HR putIfAbsentAsync not enforcing withFlags(Flag.FORCE_RETURN_VALUE)

given the following HR client code

NotifyingFuture<String> f1 = cache.withFlags(Flag.FORCE_RETURN_VALUE).putIfAbsentAsync(key, "1");
System.out.println(f1.get(10,TimeUnit.MINUTES));
NotifyingFuture<String> f2 = cache.withFlags(Flag.FORCE_RETURN_VALUE).putIfAbsentAsync(key, "2");
System.out.println(f2.get(10,TimeUnit.MINUTES));

both prints print null, where the second one should print "1"

only when props.put("infinispan.client.hotrod.force_return_values","true") is set specifically when building the CM then the calls work