Can judge / probation do this?

Based on your account, as you were not convicted of any offenses and the charges were settled three years ago, however lucky you were to receive the misdemeanor plea bargain and the official declaration from the court not to proceed on the felony offense (the nolle prosequi), the Arkansas court's recent demand seems improper. Still, if you fail to appear a warrant for your arrest will be issued. You need an attorney, and as this is a criminal case you should be entitled to a public defender. Contact the public defender's office in the Arkansas jurisdiction where the case is being heard and explain it to them. If you don't have an attorney on this, the court and the prosecutor will eat you alive.