Empty timeline view, empty dates view - but can search for dates?

Hi list,

I have been using digikam for ages now but at some point the timeline view (and the dates view) suddenly became empty. I 
have checked with the DB (MariaDB) that dates are included, also they are properly shown in the overview and I can even 
search for pictures in a timeframe.

I have no clue what might be a reason for this.

I'm running mostly on gnome on debian unstable but using plasma or Xfce doesn't change a thing. I'm aware that unstable 
occasionally breaks things but this issue persists now for a longer time so I'm afraid it's probably some local 
configuration issue. My pictures reside on an NFS share from a NAS. As said, I have no clue where to start looking. 
Pointers welcome.

TIA
Chris.