Randomly no alert sound & vibration while receiving messages from apps like Whatsapp, Telegram, Messenger etc. This is happening with many devices. Problem is related to Android.https://issuetracker.google.com/issues/139212329

They said, they are not responsible.on call, they said talk with google directly

Randomly no alert sounds from different communication apps like Whatsapp, Telegram, Hangouts etcMessage comes in phone but without alert sound & vibration randomly.https://issuetracker.google.com/issues/139212329

yes, issue is related to Android. But still, we as a end user are not authorized to talk with Google directly.Samsung is OEM, so I think it is the responsibility of Samsung to solve or get it solved from Google

This is android bug, please star mark the issue on Google forum link below https://issuetracker.google.com/issues/139212329