I had the same issue. I finally founded the temporary solution.I rolled back to old version 2.18.122
It have no issues.... Download old version of whatsapp from apkmirror. Hope it helps..
---------- Post added at 02:31 PM ---------- Previous post was at 02:19 PM ----------
I used different mobile like sony,honor but issues are still there. Problem is with whatsapp new version, not your mobile device... Switch to old version of whatsapp as possible to solve the issue..I am using 2.18.122...now no issues.
I will try download that version... u are using 2.18.122 for how long ? And really no issues ? No missing chat randomly? I try like a lot but nothing help... will do download your version soon. Thx 4 ur help ...