LG ISSUE IS NOW FIXED!
Please upgrade to version 9.8.10, now available on the PlayStore. And please post here to let us know if this new version works for you or not.
Note: We know of one LG device that is still experiencing an issue with keeping the Lock. But for the other 5 LG devices that we know of, version 9.8.10 now fixes the issue. We are actively working with this one device, to see if we can get it working as well.