Cannot recognize JSON with many Cyrillic characters

[FranklinYu]

https://unicode-table.com/en/#cyrillic

Try adding ЀЀЀЀЀЀ into the JSON response and the "JSON Beautifier" tab won't show.

[JacobReynolds]

Burp won't allow me to paste those characters into the response windows. Did you configure specific unicode settings to allow it?

[FranklinYu]

No, I don't think there is such settings. Burp itself is terrible at Unicode. I simply intercept some JSON response and add those characters. I suspect that pasting Unicode isn't supported either, so I paste Base64 encoded text (0IDQgNCA0IDQgNCA), and hit Ctrl + Shift + B to decode it in proxy intercept tab. Neither copy nor paste of Unicode works in Burp.

This bug only happens to HTTP response, according to my experiments.