Forgive me but a tyro's view is

On the Dell remote, is their separate power on/off buttons?

If no - 90%+ chance there are no discreets
If yes - 90%+ chance there are discreets

I am going to presume there are not discreets.

1st item: does the supplied remote correctly control power?

We will presume yes
2nd item: I am not as familiar with the mx-850, but have successively programmed many a TOAD in Pronto. Can you specifically subscribe to the fact that the code was learned correctly?

I ask as at least in Pronto macro world, I need to allow for "incindental" various power on/off functions in a time allotment. (IE: My Denon needs 2 secs to recognize a power on/off function before executing other macro based functions to that component).

View it as Apollo 13, its not what you turn on, but in what sequenece and how.