When tracking is enabled, it seems that links are redirected through a non-HTTPS site. This will cause the latest version of Google Chrome to block download links through email with tracking enabled. This may happen with live chat too, I am not sure.
Our customers are not able to download files from us if they are using Google Chrome and it's causing issues for us.
I am hoping that HubSpot can create a fix for this and redirect links through a secure site.