Reported by snow wolf, 17th Dec 2017, in email on feedback@.  That report includes an mp4 video showing the steps.

Quote:
"I'm using Audacity ver2.2.1 downloaded from fosshub in Windows 10 64bit. I
found Karaoke command and in order to use it I created a label track and
used Ctrl+B to create a label. But when I was trying to type in the text
edit widget popped up on the label, with an IME
<https://en.wikipedia.org/wiki/Input_method>, it fails, only default
keyboard is typed in. It just does not accept input from IME, yet other
edit widgets can accept IME input. It may be a little difficult for
alphabetic script users to imagine what is an IME, so I recorded a video so
that you can understand what happened (video volume caution, very loud).

In some software, like Web Browser in Steam. It supports a little text edit
dialog at the top-left corner, although I don't like it, it can at least
get input. Similar thing appeared accidentally in the video, maybe it is
focused on a mysterious input widget of Windows. But IMO, the best result
is let it affect as normal text edit widget, directly input words in it,
rather than a top-left input box."