Expected behaviour
Normally, applets on Mate-Panel should remain there all the time at every boot.
Actual behaviour
Applets just disappear/appear randomly at every boot/reboot. Sometimes clock is gone. Sometimes hardware sensors says bye bye. Sometimes things crash. It's a problem that was there since GNOME 2.32, and now on MATE its the same.
Steps to reproduce the behaviour
Having some applets (stock one too) and just Boot/reboot. It will happen.
MATE general version
1.20.1. Latest one.
Package version
idk.
Linux Distribution
Ubuntu MATE 18.04.1 LTS with all the updates applied.
Link to downstream report of your Distribution