It actually isn’t compatable until 1.4

dd-java-agent/instrumentation/hystrix-1.4/hystrix-1.4.gradle

@@ -3,10 +3,9 @@ apply plugin: 'version-scan'
 versionScan {
   group = "com.netflix.hystrix"
   module = 'hystrix-core'
-  versions = "[1.3.15,)"
-  scanMethods = true
+  versions = "[1.4.0,)"
   verifyPresent = [
-    "com.netflix.hystrix.strategy.concurrency.HystrixContextScheduler\$ThreadPoolWorker": "schedule",
+    "com.netflix.hystrix.AbstractCommand": null,
   ]
 }
 

dd-java-agent/instrumentation/hystrix-1.4/src/main/java/datadog/trace/instrumentation/hystrix/HystrixThreadPoolInstrumentation.java

@@ -1,5 +1,6 @@
 package datadog.trace.instrumentation.hystrix;
 
+import static datadog.trace.agent.tooling.ClassLoaderMatcher.classLoaderHasClasses;
 import static net.bytebuddy.matcher.ElementMatchers.isMethod;
 import static net.bytebuddy.matcher.ElementMatchers.named;
 import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
@@ -31,8 +32,8 @@ public class HystrixThreadPoolInstrumentation extends Instrumenter.Configurable
     return agentBuilder
         .type(
             named(
-                "com.netflix.hystrix.strategy.concurrency.HystrixContextScheduler$ThreadPoolWorker"))
-        // Not adding check for classes on the classpath because this is the only class we need.
+                "com.netflix.hystrix.strategy.concurrency.HystrixContextScheduler$ThreadPoolWorker"),
+            classLoaderHasClasses("com.netflix.hystrix.AbstractCommand"))
         .transform(DDTransformers.defaultTransformers())
         .transform(
             DDAdvice.create()

settings.gradle

@@ -13,7 +13,7 @@ include ':dd-java-agent:instrumentation:apache-httpclient-4.3'
 include ':dd-java-agent:instrumentation:aws-sdk'
 include ':dd-java-agent:instrumentation:classloaders'
 include ':dd-java-agent:instrumentation:datastax-cassandra-3.2'
-include ':dd-java-agent:instrumentation:hystrix-1.3.15'
+include ':dd-java-agent:instrumentation:hystrix-1.4'
 include ':dd-java-agent:instrumentation:jax-rs-annotations'
 include ':dd-java-agent:instrumentation:jax-rs-client'
 include ':dd-java-agent:instrumentation:java-concurrent'