My son's AROTC experience was never called "probation", but it could be applicable to your situation...He had attended his university for two years before he took a military LOA to enlist. His BCT and AIT ran for 16 months, so he returned too late to start the Fall semester. When he contacted ROTC to let them know he was interested in joining, they asked him if he could start in January as an uncontracted 200 cadet. There was another Reservist in the same situation. The school's reasoning for this "trial semester" was that they had already committed to sending far more 200 cadets to summer training than they had contract slots for 300's available the next Fall. This gave the school at least a semester to evaluate the two new soldiers. Both were contracted/enrolled in SMP before the Spring semester was over, and the cuts were made from others who needed to attend summer training. While it did add a semester to my son's program, it gave him the time to lower his course load over the 5 remaining semesters and raised his CGPA significantly...