I've called once on probation. It was a day prior to beginning reserve and there was a huge ice storm forecast for ATL. I had the JS reserved on a flight that was supposed to depart 2 hours before the storm was supposed to hit and there was a legal backup with spots available 2 hours after my primary departure time. Well, scheduling ends up cancelling my primary about 4 hours prior to departure, I was still able to reserve the JS on my backup which was then showing delayed 4 hours. I called scheduling and they PS'd me on the 1st available flight to LGA from ATL. There was no pushback from scheduling, I never heard anything negative from my chief pilot, and it wasn't even brought up at my regularly scheduled probationary chief pilot meeting a couple months later. Just 1 data point, but from my brief experience if you play by the rules the company will honor their side of the agreement without repercussions, even if you are on probation.