The following steps should work.
1. Navigate to /components/com_comprofiler/plugin/user/plug_pms_mypmspro/templates
2. Create a folder named "custom"
3. Copy "messages.php" from "default" folder to "custom"
4. Edit "messages.php" in "custom" making the following change
FROM:
Code:
<div class="col-sm-auto d-block d-sm-none pmMessagesRowDate">
<?php echo cbFormatDate( $row->get( 'date', null, GetterInterface::STRING ), true, false ); ?>
</div>
TO:
Code:
<div class="col-sm-auto d-block d-sm-none pmMessagesRowDate">
<?php echo cbFormatDate( $row->get( 'date', null, GetterInterface::STRING ) ); ?>
</div>
5. Within CB > Private Messages > Parameters > General set "Template" to "custom"
That should now have it to display time when viewing the messages list. You'll need to do similar for cbFormatDate if you also want it to show time when viewing the message directly in "message.php".