blender doesn't show me some parts

[Davide]

hi guys, I'm new in this forum but I use draw by 1 month...  initially build the models with lego digital designe and then I import them in blender thanks to ldraw ... I have only recently noticed that the parts: 18973, 27507 and many others are not displayed in blender ... practically the dat extension files present in the library there are not in the window at the top right: Collection / scene collection .. only the file name extension ldr appears to me.
Have any of you encountered the same problem?
thanks
 David