Irene2_ASUSHi there, wow that's new... I don't know you can reset "adaptive brightness" only. Thanks, Irene but the issue still persists. I think it's a bug within this update. I use this phone for almost 2 months now and always update whenever there's a chance. I can confirm that previous version (WW_18.104.22.168) worked great for me, maybe the best so far because before that version there were problems as well but I forgot.
Please try the following steps;
1) Double-check that you have Adaptive brightness enabled by going to Settings -> Display -> Adaptive brightness
2) You can reset adaptive brightness by going to Settings -> Apps & notifications -> Se all XX apps -> Device Health Services -> Storage & cache -> Clear storage -> Reset adaptive brightness
I hope that solves your issue, otherwise let me know 🙂