Try for example from menu "File -> Import -> Insert Image": file dialog ALWAYS opens with "BW" image type in File Filter (maybe this is first entry in FilteIndex), so you always must expand File Filter list and scroll to type you needed.
After dialog opens FileFilter must be "All Image Files", or better: dialog must remember last File Type used.
Please add some more information about your OS and LibreCAD version.
There was a fix in January 2015 concerning this after release of 2.0.7.
So in nightly builds it should work well.
See https://github.com/LibreCAD/LibreCAD/issues/486
Sorry, forgot.
my system is KUbuntu 14.04.2 LTS; 3.13.0-61-generic #100-Ubuntu SMP
From LCAD About dialog (installed from Nightly repository):
Version: master
SCM Revision: 2.1.0
Compiler: GNU GCC 4.8.4
Qt Version: 4.8.6
Compiled on: Jul 31 2015
I also tried from menu "Draw -> Insert Image..." and got same result as "File -> Import -> Insert Image": File of Type after file dialog open is always "BW".
Last edit: Valdas Jankūnas 2015-07-31
I can confirm the master branch works for me on Linux.