The basic firmware is the same on all Kobo models running that firmware version.
Where are you sending the kepubs to on your Clara HD? What is the template you are using in the KoboTouch driver? I've attached an image of the first configuration page for the KT driver as I have it configured.
When you mount the device on your computer, can you see the kepub file in Finder? What version of calibre are you running? You mention 7.7.1 but that is not a calibre version (6.25 is currently the latest version and it should run on your machine).
The only reason for disabling the KoboTouch driver would be if you were using the KoboTouchExtended driver which will convert epub to kepub as they are sent to your Kobo.
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