I've been having the same issue too, hadix, and have found nothing on pdf24's website to address the question.
And you've received no response find 2/15, and here it is 4/3!
Do we need to speak German? 😉
It started for me when I uninstalled _ALL_ of Adobe's stuff, and installed pdf24.
BTW, congrats on finding your way here; if I hadn't used a search engine, I could not have found the Help center, even with a fresh account. Guess I haven't mastered the "dashboard" yet.