In https://en.wikipedia.org/w/index.php?title=Bombo_railway_station&oldid=870980076 in the section "Platform building (1887), the architectural term "facade" is written in the French form "façade" with a cedilla (the curly thing under the "c").
I tried to link this to the Wikipedia article "Facade". I did this by selecting the text and then clicked the Link icon on the tool bar. The normal link dialog pop-up appears
As you can see, the text in the search box is "Faade" and the suggested links are not what I want. I'm not sure whether I'd call this a bug at this point. As a user just trying to get a job done, I said to myself "Ah, the cedilla is confusing it, but that's OK, I'll just type in the word "facade" into the search box. I did this and I get this:
The desired article "Facade" (exterior side ...) is there, I click it, thinking all is well. But then I find that clicking "Done" does nothing, clicking "Cancel" does nothing. The Link pop-up is determined to stay put. However I can click outside of it (the Link pop-up remains) and take a look at the article and I see that "façade" is now a red link (why?) and Publish Changes is blue (so VE thinks a change has been made, fair enough). Anyhow (as I had done other edits that I wanted in other parts of the article), I published the changes and then looked at the article in source editor and found the change that had been made was
A check of the previous version (before my edit described above) in source editor confirms that the word had been written as
and perhaps it was the HTML representation of C-with-cedilla that was the problem. Interestingly, if I switch into source editor after I try to link to Facade and have the sticky Link box problem but before I "publish changes", I do not see the link to Faade at all, just unlinked façade is present in the text. So the source editor doesn't seem to think any change was made, yet Publish Changes in VE thinks I wanted a link to Faade.
I then experimented to try to fix the problem (correct the link to be "Facade" in a subsequent VE edit) but the same sticky Link box resulted (as described above) and there was no change to the linked article. After a bit more experimentation, I gave up and fixed it in the source editor. I do not think there is a way to link that word (or change the link once it is Faade) in the VE.
Windows 8.something, whatever is current. Vector. Chrome version Version 72.0.3626.119 (Official Build) (64-bit)