Zwift/ elite power delay

I posted a couple of weeks ago about the trouble I was having with a new elite zumo, basically the Watts were around 30 lower than my power meter.
Got in touch with elite who were great, asked me to perform a routine on the elite app and send them the tcx files for both the zumo and 4iiii. They got back to me with a firmware update which has solved the wattage problem, great. Unfortunately now, zwift is taking an age to register an increase in power in sim mode, haven’t tried erg, if I get out of the saddle and sprint, the power meter, using my garmin, shows the power instantly, the power on zwift doesn’t get any where near my peak power before I back off. Its as if the power has been smoothed by 10 seconds.
I’ve tried Windows and android, Bluetooth and Ant+, the same. It works perfect with the elite app so I’m guessing there’s some problem between the trainer and zwift.
Can anyone help before I get back in touch with elite.