object disappear (merge) after 1st frame

Hi there,
I have a problem with my little animation… A buch of falling cubes (rigid) onto a moving plane and after the first frame, the cubes disappear for some reason… I could not find similar thread here. Any tips much appreciated… :slight_smile: attached frame1 and frame2… thanks a lot

Attach or post a link to your blend file

here is the file, Pasteall allows max 30MB…:


or here.

thank you