Kmail notifier lacks numbers - and is transparent

[Zelator57]

After finally upgrading to 17.03, the Kmail email notifier stopped showing the number of new emails. In an effort to fix this I tried changing the desktop themes. Now, whatever theme I use, the Kmail notifier is transparent, so to see it at all I have to use a light theme, currently Breeze. I can't get back to the original theme, in which the notifier was yellow.

I will get used to light themes, I've had them before, but I would appreciate the email numbers back.