Sinch E-mail 365 issue with receiving campaign metrics

We recently implemented Hybris/SAP Marketing on-premise (1709) and are looking to implement Sinch E-mail 365 as our ESP (Email Service Provider). We've run into several major issues, one of them being unable to receive "email Opens". We receive it if a customer clicks on a link in the email, but that's pointless, because the "Opens" help us strategize subject lines/content (A/B testing and changing what we send). Do you have any suggestions on how to fix this?

We currently use IBM Watson Campaign Automation/Silverpop that's super mature, so this seems like an expensive downgrade. Silverpop and other mature ESPs add a 1x1 tracking pixel to track Opens, but that basic functionality seems to be missing.