No tray icon on Linux Mint

[tiaga]

Since 1.0.216 Joplin's icon cannot be found in a tray on Linux Mint 19.2 with Сinnamon desktop environment.

Environment

Joplin version: 1.0.220
Platform: Linux Mint 19.2 Tina
OS specifics: Сinnamon desktop environment

Steps to reproduce

1. Install Joplin using Joplin_install_and_update.sh and run it.
2. Go to "Options > Application" and check that "Show tray icon" is enabled.
3. Restart the application.

Describe what you expected to happen

Joplin's icon is shown in a tray on Linux Mint 19.2 Cinnamon (as it was in previous versions).

Logfile

debug.log on Pastebin

[dpoulton-github]

Appears to be a duplicate of #3242 which discusses an upstream issue causing this behaviour.

(See also: https://discourse.joplinapp.org/t/joplin-1-0-214-no-tray-icon-on-linux-mint-19-3/8865)

However I have tried Joplin with the Linux Mint 20 beta and not only does the icon show it also starts Joplin just by clicking it (ie no need to right-click "open")