No it doesn't open in a private window.
But nonetheless the strangest thing happened.
I tinkered around with even more settings, notably the one i missed and it was the 'Block ads' tab. When i turned it off the site suddenly started to load! I now to have add that site as an exception.
But i don't understand why this site would be an ad... but i'm not a website expert so... in the end I solved my own problem.
Thanks for taking the time to help leocg.