Content Query Web Part (CQWP) not showing all columns for filtering

After adding a CQWP on my page and specifying a source, I tried to select metadata columns; however I could not find those in the dropdown. Metadata columns were somehow not listed in the dropdown. I followed below steps to get all the columns listed in the dropdown for selection –

1. Export the CQWP.

2. After exporting CQWP, open it with a notepad and search for the below line –

      <property name="CommonViewFields" type="string"/>

3. Replace this line with below  text–

<property name="CommonViewFields" type="string">
ExternalUrl,URL;PublishingPageImage,Image;Body,Description;PublishingPageContent,RichHTML;PublishedDate,   DateTime;Author, User;
</property>

Save and import the modified web part. Add this modified CQWP to your page and voila, now you can see all the fields in the dropdown for selection.