Shutter icon in System Tray ubuntu 20.04.2 LTS

Up to a few days ago when there was an update to Shutter there was an icon in the System Tray

However, since the update, this icon fails to appear even though the setting are correctly configured in Behaviour

Restarting the PC has no effect.

I can select Shutter to appear in the dock as a favourite and launch it from there but the setting to launch at login appears to be ignored whereas in the past it worked perfectly well in the system tray.

Another anomaly is that on my scratch PC with ubuntu MATE 21.04, it works correctly - the icon appears in the top panel (MATE equivalent of systray).

I'd be grateful for any pointers as to what I may have missed. Both versions of Shutter (ubuntu 20.04 and MATE 21.04) are the same

I have checked the settings on both systems and they are the same.

UPDATE:

I reported the issue and it is suggested that this may be associated with libappindicator. Are there some simple steps to achieve this?

The solution to installing the app indicator in 20.04 (and 21.04) is to ensure that appindicator is up to date by installing gir1.2-appindicator3.

Open a terminal and type the following commands:

sudo apt update
sudo apt install gnome-shell-extension-appindicator

Then install gir1.2-appindicator3:

sudo apt install gir1.2-appindicator3-0.1

Then launch Shutter and the app indicator will be be restored to the system tray.