My last race had a 20min power that should have resulted in an FTP bump but I didn’t see the usual FTP increase detection. I did 298W according to zwift power for ftp = 298*0.95=283, while my profile shows my FTP at 280W. Not a huge issue, but in case it’s a bug…
I had the same issue happen to me a few days ago. Both my hour and 20 min FTP for the ride were enough to increase it, but nothing happened.
Best guess is, your VI was too high.
Indeed, let’s say someone performs a standard ftp test, and by the end of 20min he/she decides to do an all out sprint, then obviously the final result will be greater (yay), but from scientific perspective test is failed. FTP stands for Zone 4, not an averaged mix of zones, It is a wattage, which a person should be able to stay at for at least one hour straight. And if someone forgot, FTP in first place serves to get the most out of every workout, and the goal here is to get that number as accurate as possible. Training plan success (and EGO lol) is the only thing that’s actually affected by FTP.