application records locks are NOT logged to alert_SID.log file
is table being UPDATED involved in any PK/FK relationship?
if so, does FK have a supporting INDEX?
Nothing is going to show up in the Alert log for a problem like this at least given what you have described so far.
If the logs for the application are not showing enough information maybe that logging needs to be improved or modified.
It might help if you monitor for this scenario and alert someone when it is happening rather than trying to hunt it down after the fact.