I have seen a few comments on this, without there ever seeming to be any response or good advice, but I have now replicated the same issue in two consecutive Ramp Tests.
I haven’t done a whole load of workouts in the past, but recently committed more to them, including completing the Academy Road stuff over the last few weeks and ERG Mode has worked perfectly right through.
On the Ramp Test I did a few days before starting on ZAR I noticed that the trainer didn’t seem to be properly holding/adjusting power once it got above around 300W … basically, I had to increase cadence and change gear to get up to the higher power figures (ERG mode had worked perfectly well up to that point in the ride).
When it then worked fine through all the ZAR workouts (although there were only a couple of occasions that 300W+ was needed) I thought nothing more about it.
Having decided to follow up ZAR by doing the 12 week Build Me Up plan, I did the Ramp Test again, and found exactly the same issue … ERG mode fine up to around 300W, but once above that found myself having to change gear and increase cadence to get up to the required wattage.
Running Zwift on a Win10 PC, using a Tacx Flow Smart.
The trainer is getting a bit long in the tooth, and the plan is to replace it with a Zwift Hub once they have some stock that doesn’t come in and get sold out between me going to bed and getting up in the morning.