Indeed I can reproduce that issue but I'm unsure if it's just an issue with their API or if we're using that API in a wrong way.
Fact is that it worked before and now it fails although we haven't pushed any updates for ~4 weeks.
Other open source projects using that API seem to fail too...
Here are your options for now:
1. Use website mode instead but then JD will only find the first ~30 items.
2. Use
this method as a workaround.