Are your class names obfuscated? If the class names are obfuscated, you need to make sure you use the obfuscated class names in log4j.properties too. So, if the MongoDBUtils class is using the logger named o.s.data.mongodb.core.MongoDBUtils, then in your properties file, you should put log4j.category.o.s.data.mongodb.core.MongoDBUtils.
Remember to always leap before you look. But always take the time to smell the tiny ads:
a bit of art, as a gift, the permaculture playing cards