Fix monthyear format bug

src/string_ids.c

@@ -1407,6 +1407,7 @@ void format_string_code(unsigned char format_code, char **dest, char **args)
 		formatString[0] = FORMAT_MONTH;
 		formatString[8] = FORMAT_COMMA16;
 		format_string_part_from_raw(dest, formatString, (char**)&dateArgs2);
+		(*dest)--;
 		break;
 	case FORMAT_MONTH:
 		// Pop argument
@@ -1674,4 +1675,4 @@ void reset_saved_strings() {
 	for (int i = 0; i < 1024; i++) {
 		RCT2_ADDRESS(0x135A8F4, uint8)[i * 32] = 0;
 	}
-}
+}