Display problems and other issues sometimes occur in the Visual Experience Composer (VEC) and the Enhanced Experience Composer (EEC) under certain conditions.
With the latest changes (August 2020), all users with Chrome 80+ browser versions:
adobemc.com domain. Without this attribute, the browser will reject these cookies, causing the EEC to fail.
Adobe has submitted an updated VEC Helper extension to the Google Chrome Store. This extension overwrites the cookie attributes to set the
SameSite="none" attribute, when needed. The updated extension can be found here. For more information about installing and using the VEC Helper Extension, see Visual Experience Composer helper extension.
For your own site cookies, you must specify the cookies by name. Toggle the Cookie slider to the on position, then specify the cookie by name and the cookie domain. The cookie name is “mbox” and the cookie domain is the second and top levels of the domains from which you serve the mbox. Because it is served from your company’s domain, the cookie is a first party cookie. Example:
mycompany.com. For more information, see Adobe Target Cookies in the Experience Cloud Interface User Guide.
Use one of the following options to ensure that your VEC and EEC continue to work as expected:
Download and use the updated VEC Helper extension.
Use the Mozilla Firefox browser. Firefox is not yet enforcing this policy.
Continue to use Chrome, but set the
chrome://flags/#same-site-by-default-cookies flag to “Disabled."
This will not be enough if cookies already have the SameSite attribute set to “Lax” or “Strict” from the server.
Target does not support multi-level iframes. If your website loads an iframe that has a child iframe, Target libraries (at.js and mbox.js) interact with the parent iframe only. Target libraries do not interact with the child iframe.
As a workaround, you can add a page in the experience with the URL of the child iframe.
This can happen if the URL contains a # character. To fix the issue, switch into Browse mode in the Visual Experience Composer, and then switch back to Compose mode. The spinner should go away and the page should load.
If your website’s CSP headers block Target libraries, then loads the website but prevents editing, ensure that the Target libraries are not blocked.
In addition to the following information, you can use the Adobe Target VEC Helper browser extension for Google Chrome.
As a workaround, you can configure a Requestly rule to remove CSP headers, as shown below:
You can configure a similar Requestly rule for any header that causes a resource to not load inside the VEC.
For Requestly, whenever there is a need to remove headers, you should do either of following:
If the website has changed outside of the Visual Experience Composer after the experience was defined, selectors on which actions were taken earlier cannot be found when the activity is opened for re-editing. The page appears broken, and no warning displays.
This issue happens when customers have an mbox.js version earlier than 57 (i.e. version 56 or earlier).
If the same DOM element ID is used on multiple elements on the page, changing one of those elements changes all elements with that ID. To prevent this from happening, an ID should be used only once on each page. This is a standard HTML best practice. For more information, see Page Modification Scenarios.
This issue can be addressed by enabling the Enhanced Experience Composer. Click Administation > Visual Experience Composer, then select the check box that enables the Enhanced Experience Composer. The Enhanced Experience Composer uses an Adobe-managed proxy to load your page for editing. This allows editing on iFrame-busting sites and allows editing on sites and pages where you have not yet added Adobe Target code. The activities do not deliver to the site until the code has been added. Some sites may not load via the Enhanced Experience Composer, in which case you can uncheck this option to load the Visual Experience Composer via an iFrame. 
Your locally hosted pages or pages that are not accessible outside your network are not accessible to the Adobe proxy server and cannot be opened in the EEC. These pages might include staging URLs, User Acceptance Testing (UAT) URLs, or locally hosted pages.
See “I can’t edit experiences for an iFrame-bursting site” above.
If you use Edit Text/HTML in the Visual Experience Composer for A/B or Experience Targeting activities or Change Text/HTML for Automated Personalization or Multivariate Test activities to make text bold or italic, those styles might not be applied on the page or the text disappears from the page in the Visual Experience Composer. This is because the way the rich-text editor applies these styles might interfere with the website markup.
If you see this issue:
Click the HTML button in the rich-text editor to enter source editing mode.
Find the styles text elements.
For bold text, change
<strong> elements to
For italic text, change
<em> elements to
Adding an image offer to a location takes the full dimension of the original image space in the VEC or EEC. On delivery, the image is not expanded and is shown as it is, so there is no impact on delivery.