I have had my s10 since it came out & i regret upgrading so much! I have been through all the settings and adjusted as needed but have nothing but issues with this handset.
I wish i never traded my s8 in as I miss it so much! Was so much better
We've tried all of the above and nothing. Then my wife found the "trusted devices" option.
It turns out that her fitbit charge was a trusted device so when in close proximity (so all the time really) smart lock would automatically unlock her phone.
So of this is the case try removing your trusted device and see if that works