From what that part of the logic shows, you have 6 Cooling callers but the number of significance is your Current SAT Setpt of 55F. Somewhere else on your logic page, there has to be a direct acting PID that shows the cooling demand increasing as your unit stays above the discharge setpoint. The longer the SAT is above 55, the more stages are going to come on. You mention 3 compressors for 3 zones but it shows 6 active callers out of 10. If these zones have some size to them, at 90F outside temp
If you truly have Supply and Return Fan VFDs as the graphic shows, I would keep an eye on the Static pressure because being half an inch W.C. low seems to indicate the zones are wide open and not satisfying their individual setpoints. If they run at 100% most of the time, the VFDs are just for show.