After update to 8.18 the back/lap button does NOT work anymore.

I updated 1 hour ago from 7.35 to 8.18 , restarted the watch also, BUT: when i go to glances or use the START button i can not go back again to the normal watch face with the BACK button, to get back to the watch face i have to wait till the screen turns off and then reactivates with wristmovement.

For a $1000 watch one could expect at least basic functions , even after a big update.

Anyone else have this isue ?  or is it already known ?