No notifications at all on older Facebook Messenger app For obvious reasons, I'm using an older version of facebook messenger app (ver 71)

But there are no notifications of arrived message, and important feature

If it's a bug or bad config, can be fixed ?
If not, is there a way to overcome this without third parties ?

Android M
Xperia Z3

Edit:
Tried upgrading to version 81, the last one I can tolerate the bloats, but no change

Tried messing with things like permissions, overlapping, notifications...
Nothing changes

EDIT:

It was a bug that went away after reflashing the system.
Unfortunately, I cannot tell what it is

It works now, even for very older (and better) version, like 40.0

The thread may stay open for config speculations

EDIT 2

The thing is back again. One day after a master reset it stopped working

I've tried updating to verson 90 (again, not higher, for obvious reasons, but another tolerable version), but no solution

Uninstalling/reinstalling doesn't help

Weird thing is: facebook app notifies it's own alerts, and also when a message arrives on the messenger app.
But android gets no toasts...
Did you try to use Facebook Messenger Lite ?