As a workaround, many people suggest to use the Gmail app that offers Exchange services. Alas, not an option for those who want to remain google-free.
What I didn’t know however, until someone pointed it out on this forum, is that some other e-mail apps offer complete Exchange/ActiveSync as well. I’m now testing both BlueMail and Nine Mail and there’s some others I don’t know off the top of my head. Up until now, Exchange accounts run very smoothly and have no trouble at all to put my calendar items in the native calendar. Awesome!