Hi Pere,
LibreCAD uses DXF 2007 by default. Maybe you have to resave them in DXF 2004 format.
You can change the DXF format in the save dialog.
You can check the version when you open the DXF with a text editor.
You will find this near the top of the file:
9
$ACADVER
1
AC1021
The value
AC1021 stand for DXF 2007.
For ACAD 2004 the value should be
AC2018 or less.
But you can't change this value with the text editor. The DXF 2007 format could contain codes which are unknown in DXF 2004.
When you save the drawing in an older format, LibreCAD takes care about this.
Armin
investing less than half an hour into Search function can save hours or days of waiting for a solution