Don't worry we will get to the bottom of this.
1. Are you using Ad Blocking software Extensions in Chrome?
Normally these tools will have a way to let them know that a page is safe.
Try clicking their Icon in the chrome ribbon and then click "Don't Run on this Page"
In some other tools you may have the ability to Whitelist specific domains. If this is the case,
add contactmonkey.com to this list, save your changes and refresh your chrome browser.
This should allow our sidebar to be displayed.
If the steps above don't resolve your issue. Proceed to step 2.
2. Are you using other tracking software Extensions in Chrome?
Some users may try a couple of similar tools before finding a right match for them.
If you have used other Tracking or Salesforce Integration extensions in chrome please remove them to ensure there are no conflicts with ContactMonkey. Here is how to remove an extension which is not needed:
- Open Chrome.
- Go to chrome://extensions/
- Next choose the extension you want to remove, click the trash can to remove it from Chrome.
If the steps above don't resolve your issue. Proceed to step 3.
3. Let's try clearing your chrome cache data. Something may be stuck in the sign in process.
In the top-right corner of Chrome, click the Chrome menu 
Select More tools > Clear browsing data.
When clearing the cache you should see the options like the image below. 
Please ensure 'the beginning of time' is selected. Also be sure 'Cookies and other site and plugin data' and 'Cached images and files' are checked. Please click Clear browsing data. Now close and reload Chrome. ContactMonkey should now be visible in Gmail.