Adobe Campaign, when tracking is enable in the delivery, places automatically the pixel tracking at the end of the email.
This has been implement this way in order to avoid "false positive" when emails are scan by some specific anti-virus / spam filters...
Unfortunately, today we have more & more client/webmail that are cutting off the email body if this one is too long:
famous example: gmail cut it when HTML code reaches 102 kb... And we now have Orange in Europe that does it also
Due to that, we are loosing a lot of open tracking logs if the email is too large
AC should then move the default open tracking pixel in the top of the email because the workarround is not suitable for a such product (having to create a typology rule that will add the link in the top of the delivery at start of the analysis) as you need someone with AC dev knowledge AND deliverability knowledge to put this in place for the business end users
Subject already dealt here in the past but as an E.R: