You are changing the encoding of a string or array of strings from UTF-8 to the system encoding, but the string data value contains characters not supported by the system encoding. If you choose to change the encoding anyway, any string which cannot be converted will be left in its original byte representation, and will not display correctly as a system string. For example, if you try to change a UTF-8 string containing Japanese text or emojis to a system string whose system encoding is Windows Latin 1, the string cannot be represented in that encoding. You may also encounter this issue when trying to convert strings containing controls codes or other binary data. Right-click the string and select "'\' Codes Display" from the shortcut menu to inspect the string data for unexpected content.