Not showing match with colour switch

Steps to reproduce.

Command
$ grep '\WPort\W' /tmp/test.string.txt

shows nothing (blank line) in terminal.

At the same time:
$ grep '\WPort\W' /tmp/test.string.txt | hexdump -C
00000000 67 50 6f 72 74 20 3d 20 50 6f 72 74 0d 0a |gPort = Port..|
0000000e

And:
$ grep --colour=never '\WPort\W' /tmp/test.string.txt
gPort = Port

Info about file:
$ hexdump -C /tmp/test.string.txt
00000000 67 50 6f 72 74 20 3d 20 50 6f 72 74 0d 0a |gPort = Port..|
0000000e

File is in attachment.

Expected result is to show match with colour highlight.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: grep 2.16-1
ProcVersionSignature: Ubuntu 3.13.0-66.108-generic 3.13.11-ckt27
Uname: Linux 3.13.0-66-generic i686
ApportVersion: 2.14.1-0ubuntu3.18
Architecture: i386
CurrentDesktop: Unity
Date: Thu Oct 29 18:36:08 2015
InstallationDate: Installed on 2010-09-24 (1861 days ago)
InstallationMedia: Ubuntu-Netbook 10.04 "Lucid Lynx" - Release i386 (20100429.4)
SourcePackage: grep
UpgradeStatus: Upgraded to trusty on 2014-10-03 (391 days ago)