Posted by dellus on Feb 12, 2020; 5:12pm
URL: https://forum.librecad.org/Suddenly-lines-go-to-infinity-tp5718396p5718398.html

You have Construction Layer on at  layers 0 and Dims. Switch that off. It's purpose is to help for certain operations.
By the way, you use an outdated version. Very much recommended to update to 2.1.3 or even 2.2.0 rc.