Any time I would shut the systems down, and power back up, all functions seemingly would power back up. On occasion, the circulation pump would not come back on. I naturally "assumed" (that is always my problem) that when the power shut down, how is the circuit board supposed to recognize it started hours earlier in the absence of power, as it had already started at 12 AM and was supposed to run for 24 hours. Power off, logic off, but your right, no error code.
When the power was off, and then back on, it waits to be told by the logic chip what to do for it to start up again, such as a thermal demand, or the start time. When it gets to 12 AM, it's like a puzzle coming together, it starts and runs for 24 hours continuously. Jacuzzi should be operating on the same logic.