Found this solution via : http://handshake.co.za/2017/viewing-cbr-files-in-calibre/
I recently had a problem viewing .cbr files even though I had Calibre 2.5.0 6 bit installed on my system. I discovered that each time I was trying to open the .cbr it kept adding the file to calibre, even when I clicked view from inside Calibre.
Fixing .cbr displaying in Calibre
I fixed this by changing the file association for the .cbr to use ebook-viewer.exe which is located in the x:/Program Files/Calibre2 folder on my Windows 8.1 PC.
To change which program is used to open .cbr files, find the file you want to view, right-click the file, click “Open with” and then “Choose default program…”, now choose “More options”, scroll down to the bottom of the window and click “Look for another app on this PC”, now browse to x:\Program Files\Calibre2 and choose the ebook-viewer.exe and click open.
Now you should be able to open .cbr files with Calibre.
For Apple Mac
- Right click an .cbr file
- Choose “Get info” in the menu that appears
- In the window that appears scroll down to the section “Open with:” and pick ebook-viewer from the list of apps available.
- Make sure to click on the button “Change all” just below the drop-down after you have picked the app. This ensures that osx will use this app to open .cpr files in the future.
Close the info menu and you should be set.
(OSX Yosemite; Calibre 2.7.3)