As a workaround for this bug, you can set the text italic this way (which seems to work on the broken Samsung devices):
textView.setText(setTextStyleItalic(textView.getText());
and you need this method:
public static CharSequence setTextStyleItalic(CharSequence text) {
final StyleSpan style = new StyleSpan(Typeface.ITALIC);
final SpannableString str = new SpannableString(text);
str.setSpan(style, 0, text.length(), 0);
return str;
}