Software glitch. ODU doesn't report run times correctly to the UI. Does not affect system permformance or operation.I do have a question, how are you seeing run times? When I go into the system setup, I go to furnace info and it shows cycles, ect but under AC, everything shows zeros..Very wierd..The system has been correctly identified by the control and shows no current faults.
From your description, the unit is sized right on the money, or it's a bit short. With temps pushing 95 to 100, you shouldn't be able to recover for quite some time from 80 to 76. Systems are designed to maintain when at maximum conditions. The design temperature for Austin, TX is 96. The unit should shruggle to lower the temperature.
I'm not saying that you don't have problems, but I wouldn't get excited about the lack of pulldown in the late afternoon and evening.