More power alert on ERG?

I am really struggling to work out how to use the ERG mode and feel like I must be doing something fundamentally wrong. Can anyone advise me on what i’m doing incorrectly?

Nothing I do will allow me to hit the required power and Zwift just tells me “More Power”. But I figured the point or ERG was for it to force me into correct power?

Eg Zwift will exit the warmup stage of a workout and tell to me hold say 220W .
-If I maintain my current cadence the resistance stays the same and thus I am below the required power
-If I increase the cadence then I might be able to hit the lower powers but require silly cadences well into the 100s
-If I try to shift up a gear then resistance seemingly decreases as I wont get a power increase for the same cadence. So just end up in my hardest gear but not putting out any extra power.

I am using a Elite Zumo with up to date firmware connected, via mobile phone Bluetooth, to a windows 10 machine. Thanks in advance for your time!

Erg does not care what gear you are in, watts is watts. Having used ErgVideo (another erg based software solution) for many years I have found that it’s best to “spin up” a bit before the effort, like 95 or so rpm. For me in erg about 93 rpm works best and do not drop below 80 or so rpm or you enter the “death spiral.” I have not done an erg workout in Zwift in a long time since I use ErgVideo. You should be able to maintain the required wattage at almost rpm but it will be very different from 85 to 95 rpm.