Toolbox tray icon is extremely large (Ubuntu Budgie)

The Toolbox icon is expanding the top panel. 

I'm using Ubuntu Budgie 18.04.1 LTS. I used to have this kind of problem in elementary OS but I could handle with that by restarting the app. 

I guess the issue is confirmed fixed for Budgie 17.04 but it's not fixed for 18.04.1. Does anyone know how to solve it?

Thanks.