Thanks, I had completely forgotten about the PHP error logs when I was working through this! Luckily, changing the System Event priority to 1 has been working for the last week. If I find some time, I might do some more digging into why having it at 0 wasn't working.
For anyone that may come across this thread in the future, this is the full code I eventually ended up going with. There might be something more efficient, but it works and doesn't slow down save times that I've noticed.
<?php
$contentId = $modx->resource->get('id');
$tv_guideParentID_ID = 48;
$tv_guideParentID = $modx->getObject('modTemplateVar', $tv_guideParentID_ID);
$tv_guideParentID_val = $tv_guideParentID->getValue($contentId);
$tv_guideChangeLog_ID = 37;
$tv_guideChangeLog = $modx->getObject('modTemplateVar', $tv_guideChangeLog_ID);
$tv_guideChangeLog_val = $tv_guideChangeLog->getValue($contentId);
//$modx->log(modX::LOG_LEVEL_ERROR,'recentChangeDatePopulate ran');
if($tv_guideChangeLog){
if(!empty($tv_guideChangeLog_val)){
$changeDate = $modx->runSnippet('getImageList',array(
'docid' => $contentId,
'tvname' => 'guideChangeLog',
'tpl' => 'guideChangeLogDateNoFormatTpl',
'reverse' => '1',
'limit' => '1'
));
//$modx->log(modX::LOG_LEVEL_ERROR,'changeDate: ' . $changeDate);
$modx->resource->setTVValue('recentChangeDate', $changeDate);
}elseif(!empty($tv_guideParentID_val)){
//$modx->log(modX::LOG_LEVEL_ERROR,'guideParentID_val: ' . $tv_guideParentID_val);
$changeDateParent = $modx->runSnippet('getImageList',array(
'docid' => $tv_guideParentID_val,
'tvname' => 'guideChangeLog',
'tpl' => 'guideChangeLogDateNoFormatTpl',
'reverse' => '1',
'limit' => '1'
));
//$modx->log(modX::LOG_LEVEL_ERROR,'changeDateParent: ' . $changeDateParent);
$modx->resource->setTVValue('recentChangeDate', $changeDateParent);
}else{
$pubDate = $modx->resource->get('publishedon');
//$modx->log(modX::LOG_LEVEL_ERROR,'pubDate (nolog noparentid): ' . $pubDate);
$modx->resource->setTVValue('recentChangeDate', $pubDate);
}
} else {
$pubDate = $modx->resource->get('publishedon');
//$modx->log(modX::LOG_LEVEL_ERROR,'pubDate (nolog): ' . $pubDate);
$modx->resource->setTVValue('recentChangeDate', $pubDate);
}
