Damn video didn't work, looks like it threw it away
(double pressed share and then "rage quit" from the race after I had finished my tests without stopping the recording, and then the video was nowhere to see
).
Anyway it looks like it doesn't work at all in Sport mode. I tried right on the first lap after the start and it didn't work, then went to the pit, didn't change tires, then tried again, and again it didn't work.
Also the menu looks different, or were there always only 3 sub menus in Sport mode (Options being the middle one). I never even went to the menu during Sport mode before. I am used to more sub menus from practice and also the videos posted here showed more sub menus, but probably they were all from private lobbies.
Anyway, unless I did something wrong (but don't think so, as in the private lobby in the outlap I *did* get it to work) this will not work in Sport mode on regular laps and also not on outlaps - at least not if you don't change the tyres. Maybe they implemented another workaround for that.
One could try if it would work if you DO change the tires, but even if it worked it wouldn't really help a lot.