FetchAndLock with long Polling timeout feature - asyncResponseTimeout

Hello,
I am using C# micro services to communicate with the Camunda Rest API layer.
I am using Camunda version 7.9 which added a new feature for the FetchAndLock request,

asyncResponseTimeout The Long Polling timeout in milliseconds.
Note: The value cannot be set larger than 1.800.000 milliseconds (corresponds to 30 minutes).

Sadly I am having an issue, this is the error i am getting on the running instance of the camunda ( on tomcat ).
Is there any information or documentation which I can use to understand better how this feature works?
And what might cause such an error? Because it usually leads to fetchAndLock requests not getting external tasks anymore even although I can see in the cockpit that there are tasks.
Basically the Camunda service becomes ‘stuck’ until I reset it and sometimes need to also remove existing process instances and rarely also delete the camunda database ( because of some sort of corruption ).

26-Jun-2018 15:14:37.297 SEVERE [FetchAndLockHandlerImpl] org.jboss.resteasy.logging.impl.Slf4jLogger.error Unhandled asynchronous exception, sending back 500
org.jboss.resteasy.spi.UnhandledException: Response is committed, can’t handle exception
at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:165)
at org.jboss.resteasy.core.SynchronousDispatcher.asynchronousExceptionDelivery(SynchronousDispatcher.java:419)
at org.jboss.resteasy.core.AbstractAsynchronousResponse.internalResume(AbstractAsynchronousResponse.java:189)
at org.jboss.resteasy.core.AbstractAsynchronousResponse.internalResume(AbstractAsynchronousResponse.java:179)
at org.jboss.resteasy.plugins.server.servlet.Servlet3AsyncHttpRequest$Servlet3ExecutionContext$Servle3AsychronousResponse.resume(Servlet3AsyncHttpRequest.java:92)
at org.camunda.bpm.engine.rest.impl.FetchAndLockHandlerImpl.acquire(FetchAndLockHandlerImpl.java:91)
at org.camunda.bpm.engine.rest.impl.FetchAndLockHandlerImpl.run(FetchAndLockHandlerImpl.java:63)
at java.lang.Thread.run(Unknown Source)
Caused by: org.apache.catalina.connector.ClientAbortException: java.io.IOException: An existing connection was forcibly closed by the remote host
at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:298)
at org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:261)
at org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:118)
at org.jboss.resteasy.plugins.server.servlet.HttpServletResponseWrapper$DeferredOutputStream.flush(HttpServletResponseWrapper.java:52)
at org.jboss.resteasy.util.CommitHeaderOutputStream.flush(CommitHeaderOutputStream.java:78)
at com.fasterxml.jackson.core.json.UTF8JsonGenerator.flush(UTF8JsonGenerator.java:1022)
at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:891)
at com.fasterxml.jackson.jaxrs.base.ProviderBase.writeTo(ProviderBase.java:635)
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.writeTo(AbstractWriterInterceptorContext.java:129)
at org.jboss.resteasy.core.interception.ServerWriterInterceptorContext.writeTo(ServerWriterInterceptorContext.java:62)
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:118)
at org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor.aroundWriteTo(GZIPEncodingInterceptor.java:100)
at org.jboss.resteasy.core.interception.AbstractWriterInterceptorContext.proceed(AbstractWriterInterceptorContext.java:122)
at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:99)
at org.jboss.resteasy.core.SynchronousDispatcher.asynchronousDelivery(SynchronousDispatcher.java:406)
at org.jboss.resteasy.core.AbstractAsynchronousResponse.internalResume(AbstractAsynchronousResponse.java:175)
… 4 more
Caused by: java.io.IOException: An existing connection was forcibly closed by the remote host
at sun.nio.ch.SocketDispatcher.write0(Native Method)
at sun.nio.ch.SocketDispatcher.write(Unknown Source)
at sun.nio.ch.IOUtil.writeFromNativeBuffer(Unknown Source)
at sun.nio.ch.IOUtil.write(Unknown Source)
at sun.nio.ch.SocketChannelImpl.write(Unknown Source)
at org.apache.tomcat.util.net.NioChannel.write(NioChannel.java:134)
at org.apache.tomcat.util.net.NioBlockingSelector.write(NioBlockingSelector.java:101)
at org.apache.tomcat.util.net.NioSelectorPool.write(NioSelectorPool.java:157)
at org.apache.tomcat.util.net.NioEndpoint$NioSocketWrapper.doWrite(NioEndpoint.java:1184)
at org.apache.tomcat.util.net.SocketWrapperBase.doWrite(SocketWrapperBase.java:691)
at org.apache.tomcat.util.net.SocketWrapperBase.flushBlocking(SocketWrapperBase.java:628)
at org.apache.tomcat.util.net.SocketWrapperBase.flush(SocketWrapperBase.java:618)
at org.apache.coyote.http11.Http11OutputBuffer$SocketOutputBuffer.flush(Http11OutputBuffer.java:553)
at org.apache.coyote.http11.filters.ChunkedOutputFilter.flush(ChunkedOutputFilter.java:157)
at org.apache.coyote.http11.Http11OutputBuffer.flush(Http11OutputBuffer.java:216)
at org.apache.coyote.http11.Http11Processor.flush(Http11Processor.java:1102)
at org.apache.coyote.AbstractProcessor.action(AbstractProcessor.java:347)
at org.apache.coyote.Response.action(Response.java:209)
at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:294)
… 19 more