Environment

Windows build number: Version 10.0.18362.720
Windows Terminal version (if applicable): Commit 2af722b

Steps to reproduce

1. Install the Japanese language pack.
2. Open a cmd shell in conhost (built from source).
3. Open the Properties dialog and change the font to MS Gothic.
4. Switch the input language to Japanese Microsoft IME.
5. Make sure the IME option is initially Half-Width Alphanumeric.
6. Type abcdefgh
7. Move the cursor back to the start of the line.
8. Switch the IME option to Hiragana.
9. Type sushi then press Esc to close the IME.
10. Press Esc again to cancel the added text.

Expected behavior

In the process of typing sushi, the latin characters abcdef will be temporarily overwritten, but after step 9, I'd expect the ef restored, and only the abcd overwritten with すし. After step 10, I'd expect to see all the latin characters restored.

This is what those two steps looks like in the cmd shell in my current version of Windows.

Actual behavior

After step 9, the ef characters have been replaced with blanks, and after step 10 they're still blank.

What is weird is that I tried reverting the code back to the first public commit and it still seems to have that problem. I would have thought the cmd shell that shipped with Windows was much more recent than that. So I don't know if maybe it's just something about the build process that I'm getting wrong.