Posted by Rallaz on Jan 28, 2014; 8:07pm
URL: https://forum.librecad.org/The-chosen-Entity-is-not-and-Atomic-entity-or-cannot-be-trimmed-tp5709441p5709445.html

A block insertion ( complex entity ) or dimension (another complex entity ) can't be trimmed.

First, explode it to convert it as single entities then trim