If you're sure that it happens only in one browser, then open a bug with DayCare.You may test with an updated version of Chrome or AEM ServicePack, if that issue is already fixed & released.Alternatively, for time being, you could use a different browser to continue with your development.

Does this behavior happen with admin credentials?Could you investigate the XHR call to see your collection is getting picked up or not? Is your collection getting created at same location as other available collections?

Use negative margins for your background. To avoid horizontal scrolling, set overflow-x:hidden on both the html and body elements.check - Full Browser Width Bars | CSS-Tricks

I couldn't find a newsletter template for "We-retail" reference implementation like Geomettrix had. You could install Geomettrix from packageshare for testing purpose or create your own template using new standard practices.The underlying implementation is still similar to what used to be in earlier...

You may simulate A/B tests using OOB AEM engine but to perform actual A/B tests, either buy a license of Target or some other third party tools like Optimizely, VWO etc.  Any SaaS which fits your budget and requirements that matches your organizational goals.Couple of tools may be available for a fr...

Did you enabled "Public Collection" checkbox while creating it? It could possibly be a private collection vs public collection behavior.

Can you reproduce this in all browsers?

I'm not sure of your design when you say then you plan to use sling:vanityPath via page properties. Using this approach you can configure a vanity on a target page url. You'd still need to find a solution for appending your query string which can be done using additional redirect or post-processors....

There are multiple solutions to achieve this. It depends on your requirements  e.g:  How many vanities would you have?How many params/Ids would you have?What is the relationship between vanity vs IDs vs target urls?I'm not sure if you are trying to marry this server-side solution with utm params or ...

This is an authentication error. Are you able to login to your Omniture account - https://sc.omniture.com/spa/index.html​  via browser using same credentials?Refer this article if you have done a server-side integration of AEM-Analytics:SiteCatalyst integration troubleshooting issuesCheck if the pro...