UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36

Steps to reproduce the problem:
1. Set up extension and add a preconnect link to an Amazon S3 bucket to background page document.head
2. Make multiple Ajax requests from background page in extension to different objects in same Amazon S3 bucket
3. Look in the console for the timing of the XHR requests.

What is the expected behavior?
I would expect the background page to have established a preconnect link with the Amazon S3 bucket, leading to zero DNS lookup and SSL handshake times.

What went wrong?
When the extension is first loaded, the first XHR request does indeed have a zero time on DNS lookup and SSL handshake. Subsequent requests have positive times, indicating that the preconnect link is not working after the first request.

WebStore page: 

Did this work before? N/A 

Chrome version: 70.0.3538.77  Channel: n/a
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: