Hi jvstratum I was able to speak with the Support team at Elastic Email (because I guessed it might also be an issue from their end) and it seems that's how they add their tracking pixel.
Checking the stats via Elastic Email's dashboard I see that the mails with the issue (opened but not read to the end) are marked as "Clicked" while those fully read are marked as "Opened".
So I guess the tracking pixel in the header records as clicked and the one in the footer records as opened (my guess).
Can Acymailing also set this up with their integration in order to receive correct data.
Acymailing just doesn't record anything. At least we should know if the user "opened/clicked" the email.
Is this a feature request or I need to still open a ticket for a temporary fix?