The latest one ui 2.0 beta THIRD is now rolling out in South Korea. Hopefully soon in India :) It brings many fixes. Above Source: https://www.rprna.com/updates/one-ui/breaking-samsung-releases-one-ui-2-0-3rd-beta-with-many-fixes-for-the-galaxy-s10-s...

Third One UI 2.0 beta update now available in Korea, great :)

It should be fix by this update: https://www.rprna.com/updates/samsung-just-releases-an-update-for-lock-screen-malfunction-error-one-ui-2-0-beta/   Sadly, I am facing this issue too, but I am using Android 9 Pie, left beta program.

I am facing same issue, I left the beta program and then rollback to Android Pie, now still my screen lock not working. 

You should update, it is important. Read here more, if you want: https://www.rprna.com/updates/breaking-samsung-rolling-out-important-biometrics-update-for-the-galaxy-s10-and-note-10-smartphones/