I had an Elite Direto. It was awful changing power as you have discovered. Sometimes taking up to 10 seconds to level out. Made intervals really diffficult. I even demonstrated it to the UK distributor on their machine on their bikes. When I showed him he was astonished. It is a bug with the trainer. Add in that there is no way to do firmware updates and you are caught. When you change cadence goes all over the place becasue the machine is slow and chasing itself.
I returned it and swaped to a Kickr Core. That has been excellent. I highly recommend it. It is chalk and cheese compared with the Elite Direto. (If you look on teh Elite forum you can probably find me explaining teh problem and complaining about it).
Bear in mind that TR actually sends its “Change power” signal 2 seconds early to try and compensate across machines. Even that did not fix the Direto. It was even worse on Zwift intervals where they do not send teh signal early, and Elite’s own intervals.
With the Kickr Core it chnaged smoothly and quickly and feels just tight and quite real. No faffing about - just increase power for the next interval and your cadence naturally sits where you want it to be.
(If you really want to show the Direto problem up, make a short 30x30 interval session where the power rises from 100w to 300w and back again. It really shows up the Direto. Try that with a kickr and it is perfect.)
You have my sympathy. Swap it.