Martin Lechner, CTO from Wikitude, informed me that they fixed the bug on their side, which prevented Leaflet Maps Marker Wikitude API-links from registering at wikitude.me.
So if you want to display your markers via Wikitude Augmented-Reality-Browser to your visitors, you can now do this again. Please see this tutorial for detailed instructions.
BTW: I´d very much appreciate some screenshots from your markers showing up on Wikitude World Browser in order to add them to the showcases page on mapsmarker.com.