for (ContentVersion cv : trigger.new)
{
	if (cv.Contact__c != null && cv.Hold__c == true)
	{
		cv.TagCsv = 'Hold';
	}
	system.debug('@@ cv.TagCsv : ' + cv.TagCsv);
}

This code has been put on ContentVersion, Before Update trigger. And this debug line: system.debug('@@ cv.TagCsv : ' + cv.TagCsv);, also shows that TagCsv field has been put value into it successfully, but when I go into the Content record, the Tags field is coming in Empty.

Is this some kind of Bug ?