So far, I've only done one Zwift short FTP test, but I get regular updates of my estimated FTP from Zwift/StravaCrickles by climbing Watopia to the radio tower via either route, as this currently takes me well over 20mins.
But currently, Strava reckons my FTP is 283W, based on strong rides in early Feb up the mountain before I toned things back a lot. Zwift and Crickles still reckon ~266W. Given how my training was reduced so much until recently, I'm going to ignore Strava's high figure. I also put on a bit of weight, SAD carb cravings and not enough exercise!
Age 44
Height 178cm
Weight 77.5Kg
FTP (estimated) 266
W/Kg 3.43