How can you be arrested for breach of probation when previous background checks did not state any such warrant?

This is quite simple. To be in breech or violation of probation, a PO doesn't have to go through the courts to arrest you. You are already in the system. All he has to do is fill out a "pick-up" order, and file it with the sheriffs department, and they will arrest you on violation of probation. The pick-up order acts as a warrant, but isn't filed with the County Clerk's office. Only a warrant can has to be issued by a judge. The pick-up order can be filed by your PO and or, if you are a minor, by your parents. A police officer, during a traffic stop can even issue a pick-up order if he personally witnessed you violating your probation. Having said all this, the simple fact is that since you are a probationer, you don't have the same rights as a person who isn't. You belong to the Department of Corrections until you are done with your sentence. Of course, the PO has a certain amount of time to file his complaint against you, if not, you have to be released from jail, and your probation continues. But, most likely, he'll have all his eggs in one basket before issuing the pick-up order.