Distribution Event listener intermitently applying custom properties

Hi, I would like to ask, we have a Distribution Event listener which is used to apply a custom property (named as lastPublishedDate) when the Distribution Event Type is "ADD". We see that it is being intermittently applied to pages once we published it. And on the logs, we get a Persistence Exception error: Unable to commit changes to session, therefore, published pages didn't have the said property. What would be the cause of this and would there be a more appropriate architecture for this funtionality? Thanks!