See Topic:Slj9sktargvx8e9o, where interwiki links are not displaying for some reason. Topic:Slja58foz7lxi0bj has the same problem, an invisible link to w:de:Lee Konitz. Actually, that is the workaround: typing w: before the link.
Topic on Talk:Structured Discussions
Did you create these links using VisualEditor? If so, I think this T95850.
No, this is wikimarkup. <-- There is an invisible link made in the markup editor. <-- with visual editor.
Well, in wiki markup [[de:Foo]] disappears, that's true on article pages too, and it's been that way forever. You have to write [[:de:Foo]]. The problem is that VisualEditor generates the wrong one right now.
Oh. That's strange. Why would it disappear like that?
Because you wouldn't want interwiki links to be displayed in the article...
Because de is a language code, [[de:Foo]] is a "language link". It means "the German article about this topic is called Foo". For example, the English article about "Dog" would have [[de:Hund]], because "Hund" is the German word for "Dog". This information is used to build the "In other languages" list in the side bar.
Because of this, you can't use [[de:Foo]] or even [[de:Foo|Foo on German Wikipedia]] as a link: it'll be interpreted as a language association thing. Instead, you have to use [[:de:Foo]] to link to that article. There are a few similar cases as well: [[Category:Foo]] means "this article is in the category Foo" whereas [[:Category:Foo]] is a link to the category page; [[File:Foo.jpg]] embeds an image whereas [[:File:Foo.jpg]] links to the image.
Admittedly, the language behavior is a bit silly for Flow posts because it doesn't make sense to connect a Flow post to an equivalent article on the German Wikipedia. But the syntax is the same: [[de:Foo]] and [[Category:Foo]] are invisible pieces of information, and to make links you have to use [[:de:Foo]] or [[Category:Foo]].
So [[de:Foo]] disappearing is considered "expected" (isn't wikitext great...), not a bug. But VisualEditor generating the disappearing [[de:Foo]] form is a bug, you would expect it to generate the non-disappearing [[:de:Foo]] form instead.
Thank you. I knew that...:P