KMail 6 does not display mail body

Hello,

I had my KMail 5 set up so that the preview pane showed the mail structure 
(text and html parts, as well as attachments etc), together with the (selected 
part's) content.

Now after having upgraded to 6.0.0, only the structure is shown, but no 
content of any of the parts. 

Turning off the display of the structure (Ctl-Alt-D) will show the content, but 
not the message structure.

Is there a way to get back the previous behavior, showing both content and 
structure?

-- 
Time flies like an arrow.
Fruit flies like a banana.