(Likely) same problem for me. Running on Pi3 with Zulu java 1.8.0_152-b76, I have been having to use alsa tools to (statically) set volume. I think it used to work long ago when I was still using Oracle java but can’t tell for sure.
EDIT: However, according to this, the same provlem happens on x86 and Oracle Java.
Calling setMasterVolume(float) gives
2018-05-23 12:11:41.149 [WARN ] [core.audio.internal.AudioManagerImpl] - An exception occurred while getting the volume of sink 'enhancedjavasound' : Cannot determine master volume level
java.io.IOException: Cannot determine master volume level
at org.eclipse.smarthome.io.javasound.internal.JavaSoundAudioSink.getVolume(JavaSoundAudioSink.java:118) ~[?:?]
at org.eclipse.smarthome.core.audio.internal.AudioManagerImpl.getVolume(AudioManagerImpl.java:184) ~[?:?]
at org.eclipse.smarthome.core.audio.internal.AudioManagerImpl.play(AudioManagerImpl.java:122) ~[?:?]
at org.eclipse.smarthome.core.audio.internal.AudioManagerImpl.playFile(AudioManagerImpl.java:164) ~[?:?]
at org.eclipse.smarthome.core.audio.internal.AudioManagerImpl.playFile(AudioManagerImpl.java:144) ~[?:?]
at org.eclipse.smarthome.model.script.actions.Audio.playSound(Audio.java:40) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.invokeOperation(XbaseInterpreter.java:1085) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.invokeOperation(XbaseInterpreter.java:1060) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._invokeFeature(XbaseInterpreter.java:1046) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.invokeFeature(XbaseInterpreter.java:991) ~[?:?]
at org.eclipse.smarthome.model.script.interpreter.ScriptInterpreter.invokeFeature(ScriptInterpreter.java:143) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._doEvaluate(XbaseInterpreter.java:901) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._doEvaluate(XbaseInterpreter.java:864) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.doEvaluate(XbaseInterpreter.java:223) ~[?:?]
at org.eclipse.smarthome.model.script.interpreter.ScriptInterpreter.doEvaluate(ScriptInterpreter.java:219) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.internalEvaluate(XbaseInterpreter.java:203) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._doEvaluate(XbaseInterpreter.java:446) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.doEvaluate(XbaseInterpreter.java:227) ~[?:?]
at org.eclipse.smarthome.model.script.interpreter.ScriptInterpreter.doEvaluate(ScriptInterpreter.java:219) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.internalEvaluate(XbaseInterpreter.java:203) ~[?:?]
at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter.evaluate(XbaseInterpreter.java:189) ~[?:?]
at org.eclipse.smarthome.model.script.runtime.internal.engine.ScriptImpl.execute(ScriptImpl.java:82) ~[?:?]
at org.eclipse.smarthome.model.rule.runtime.internal.engine.RuleEngineImpl.lambda$2(RuleEngineImpl.java:345) ~[?:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
at java.lang.Thread.run(Thread.java:748) [?:?]