By default, Google Chrome has a setting that will prevent you from reporting as an authenticated Marker.io user when using the incognito mode of the browser.
To solve this, you can simply chose to Allow all cookies, which will effectively solve the issue, or if you prefer, you can add an exception for Marker.io.
First, go to chrome://settings/cookies.
For the easiest solution, simply click Allow all cookies.
Then type or copy/paste the following in the field:
[*]marker.io. Then confirm by clicking Add.
The exception should now be listed here.
That's it! Whichever option you chose, you should now be able to report with Marker.io in incognito mode while being logged in to your Marker.io account.