Has anyone experienced inconsistencies with dates applied using the OnFieldChangeSetDate write plugin?

I am using the OnFieldChangeSetDate write plugin to set dates when topics are moved to various states. The write plugin behaves as expected when the topic is first moved to the configured state. However, when any metadata is subsequently changed, the previously set date reverts to today's date at 12:00 a.m. Even if I change the topic type (or some other random bit of metadata) rather than the workflow status, the OnFieldChangeSetDate plugin fires.

Here is an example of one of my configurations:

<plugin name="SETREVIEWENDDATE" handler="OnFieldChangeSetDate" ishcondition="ISHType in ('ISHModule', 'ISHLibrary') and ISHLevel='lng' and CurrentAction='SetMetadata'">
<description>Set the review end date when objects are transitioned to Edited Draft status.</description>
<ishfield name="FSTATUS" level="lng" />
<ishfield name="FREVIEWENDDATE" level="lng" />
<parameter name="ConditionMetadataField">FSTATUS</parameter>
<parameter name="ConditionMetadataFieldLevel">lng</parameter>
<parameter name="ConditionMetadataFieldValueType">element</parameter>
<parameter name="ConditionMetadataFieldToValue">VSTATUSEDITEDDRAFT</parameter>
<parameter name="SetMetadataField">FREVIEWENDDATE</parameter>
<parameter name="SetMetadataFieldLevel">lng</parameter>
<parameter name="SetMetadataFieldOverwriteExisting">Yes</parameter>