The Galaxy S20 Plus appears to have the same focus failure that the Ultra had. I understand that Samsung released a fix for the Ultra problem, but no such fix for the S20 Plus (nor the S20 I assume). The camera refuses to focus if you're within a foot 1/2 of the subject and it is 100% exasperating. Waiting for it to focus yields nothing, it acst like it's trying to focus but never does. I've tried trying to trick it into focusing by shifting my angle or moving around, which is tedious, often messes up the composition of my shot, and shouldn't be necessary. Tonight I looked online and found that there are hundreds of S20 and S20 Plus owners across tons of different forums who are having this exact same problem; I don't know why Samsung hasn't released a fix for these phones as they did for the Ultra. Really surprising that their flagship phone with the much touted new camera would be released with such a failure, and no fix released by Samsung. I never had problems with my Galaxy S9 Plus camera, too bad I traded that one in. I'm downloading another camera app tonight and will stop using the native S20 Plus camera. I've had enough of being frustrated.
There's no fix because there's no fault, large sensors such as these phones have, have an extremely small focal point, not good for close up / macro, as already explained numerous times by Samsung and other reviewers, and the phone itself was updated to suggest, switch to x2 zoom for those shots and move the phone back a bit.