Hi Daniël,
There is indeed an issue there, and I’m able to re-create it. It’s not exclusively WPML related only. It seems to be a problem how the URL query arguments are passed, and there is a tiny mistake where there should be an ‘&’ character instead of an ‘?’ character.
Unfortunately I cannot give you a piece of code to quick fix this one, as it’s hard-coded into the javascript files. However, I’m testing a minor update to be released later on today, and I will make sure to fix this issue with it as well.
It’s usually approved within 48 hours, but I will attach the new plugin version to this thread, once it has been uploaded for approval, so you can install it as soon as possible. I will get back to this topic within a few hours once it’s ready.