Workaround: insync icon doesn't show up in KDE's tray in Wayland session

 This is a workaround for insync icon doesn't show up in KDE's tray in Wayland session

1. Go to System Settings

2. Click on Startup and Shutdown menu on the left

3. Clik on + Add... button to add insync and then select + Add Application...

4. Select insync in the dialog and click OK

5. insync should be listed in the Autostart 

6. Click on the insync's Properties button

7. Go o Application tab and add QT_QPA_PLATFORM=xcb in the Command section as below and then click OK button to save the settings:

8. Reboot your computer. The insync's tray icon should show up in the tray.

That's all there is to it.