I do NOT know for certain as I did not find a reference to this property. As a test, I would try adding a property in the rules.xml file for the agent. I do not see this property in the rules.xml.sample file in LISA_HOME so this approach may or may not work.
Perhaps, you could add a property element to specify the option for your Agent. For example,
<?xml version="1.0" encoding="UTF-8"?><rules>
<agent guid="<yourAgentsGUID>" name="<yourAgentsName>">
<property comment="Guess at how to turn off nulls" key="lisa.agent.virtualize.include.nulls" value="false"/>
:
your other options for intercept, exclude, feature, etc.
:
</agent>
Stop / start broker and agent to pick up the new option. Try a recording and see if it solves the issue.
If this does not work for you, open a ticket with support and report back here so we all benefit from your solution.