java.util.List type process variable's updated value are not displaying neither in my custom process variable listing api using auditService nor in jbpm-console workbench.

My bpmn file is simple, I have a process variable say 'numList' of data type java.util.List. At the starting, I am initializing the 'numList' as following -

List<Integer> numListLocal = new ArrayList<>();

kcontext.setVariable("numList", numListLocal);

Within next script task I am populating the 'numList' with some Integer value and reseting it into process context as following -

numList.add(1);

kcontext.setVariable("numList", numList);

Within next script task, if I print the 'numList' it is printing correctly as [1].

But if I see the process variable value in jbpm-cosnole workbench or through my custom api it is displaying as empty array list [].

Following are the codes of my custom api for process variable listing -

public Map<String, Object> getProcessVariableMap(long processInstanceId) {

        Map<String, Object> processVariableMap = new HashMap<>();

        AuditService auditService = restRemoteClient.getAuditService();

        List<? extends VariableInstanceLog> variableInstances = auditService.findVariableInstances(processInstanceId);

        for (VariableInstanceLog variableInstanceLog : variableInstances) {

            processVariableMap.put(variableInstanceLog.getVariableId(), variableInstanceLog.getValue());

        }

        return processVariableMap;

    }

I have seen jbpm's 'VariableInstanceLog' table having empty arraylist value for the process variable 'numList'. Hence my api is displaying empty value in UI.

I am attaching my bpmn file. Can you please advise if anything I am doing wrong or there is any known issue for my above use case ?