Thanks for your question I looked at the URL above and could see you are running at.js v2.0.0
Unfortunately at this current time:
Cross-domain tracking is not supported
''' In at.js 2.x, HTTP GET is no longer used and instead we use HTTP POST. HTTP POST is now used via at.js in order to send JSON payloads to Target edge servers. This means that the redirect request to check whether a browser supports third-party cookies now breaks. This is because HTTP GET requests are idempotent transactions, while HTTP POST is non-idempotent and mustn’t be arbitrarily repeated. Therefore, cross-domain tracking in at.js 2.x is no longer supported.'''
Joshua brings up a great point in regards to cross domain not being supported in at.js 2.x per the documentation: at.js cookies
In regards to the issue at hand it is possible that you have built an infinite loop based on the entry and additional URL that we can qualify for the activity from and then we re-enter and get re-directed over an over.