The most common reason is that you are using an ad blocker, like the AdBlock plugin for Chrome, which filters and alters marketing content on the internet. Sometimes, the Banner Ads section and the banner ads on your app can get caught in the filter.
Disabling Ad Blockers
Step 1. Navigate to your Extensions page by clicking the Chrome menu button > Tools > Extensions.
Step 2. Uncheck the Enabled checkbox to the right of the ad blocker in your list of extensions.
If you have AdBlock or some other ad blocking extension running on Safari, you can disable it in one of two ways.
Step 1. Click the AdBlock hand to the left of the address bar in your browser.
Step 2. Click the Customize tab.
Step 3. Add http://eventmobi.com to the list of domains that can display ads.
Through The Menu
Step 1. Navigate to your extensions by clicking on Safari > Preferences > Extensions.
Step 2. Select your ad blocking extension.
Step 3. You should find the ability to disable or uninstall it there. In the case of AdBlock, you can just uncheck Enable AdBlock.
Just follow these steps provided by Mozilla.
If you don't believe an ad blocker is causing the problem, please contact support with screenshots and any other details about your experience, like the browser you're using.