Yes I'm having problems too it will work when I first set my face recognition but then if I mess up once it continues to mess up until I erase my face recognition and redo it. This needs to be addressed ASAP Samsung!!
I have the same issue where I can be inside my house or in a car and it is hit or Miss. it definitely does not work consistently. I use an iPhone 12 Pro as a secondary Mobil device for work and the face recognition is ridiculously fast every time and without the need to press the side button to wake up phone first. Is there a way to use this feature in my s21 without having to press the side button first?
I got a S21+. It was working fine the first day or 2 and it stopped working last night. I removed/setup the face recognition data twice and still not working. Not sure what is the problem. The only thing I can think of is that I have been putting a lot of apps/services to sleep but I don't recall putting any Samsung apps to sleep (except Samsung Pay). I hate to do a factory reset.