KDE application do not start (over SSH into jail)

Hello.

I'm a long time kcachegrind user.
I've always installed it into a jail in a remote system, which I access 
through SSH.
This was working in the past (possibly months or maybe years ago).

Now it does not work anymore: if I type kcachegrind, it just stays there 
and nothing happens.
If I press ^t, I see something like:
> load: 0.33  cmd: kcachegrind 93739 [select] 5.19r 0.04u 0.03s 0% 75044k

dbus running or not does not seem to make much difference.

The same happens for okular.
All systems are 12.3p6/amd64, but I also tried 13.1p1.

Any hint on how to solve (or at least debug) this?

  bye & Thanks
	av.