German date in heading seems to confuse parsers

While writing a page in Zim, I noticed an issue. My page has level-3 headings in the form "15. Februar 2017: some text" as sub-nodes of a layer-2 heading. I noticed that the ToC does not update on changes. I saved the document, restarted Zim and noticed that some headings changed and are not shown as headings any more, but as plain text like "10. ==== Februar 2017: foo bar ====".

I think the date confuses the parser and the parser somehow treats it as an enumeration?

Best regards,

  Martin