With a high percentage chance, when I get kicked out of a server due to instability or server resets, when I return my shortcuts hud (the bar at the lower part of the screen) disappears and does not come back when I press the shortcut (grave sign).
The only way to bring the hud back is to go into the menus, disable hud -> apply -> enable hud -> apply.
This is a very well known bug that has been discussed but I have never seen people pointing out a root cause. For me, it is the server disconnects that trigger it.
Hopefully this report helps you guy pinpoint and squash this very annoying bug...