Calling modem_info_short_get for the parameters MODEM_INFO_MCC, MODEM_INFO_MNC, MODEM_INFO_AREA_CODE and MODEM_INFO_CELLID fail. Call to modem_info_short_get works with MODEM_INFO_CUR_BAND.
I suspect the problem is in code. Tracing the MCC call shows that the call makes the correct AT query to the modem. However, the parameter returned is (rightly) a string. However the value expected for that parameter is a short so the call fails. Trying to call modem_info_string_get fails because the value is typed as a short in the parameter array.
I believe the answer is to pull the string then convert into a short. Or retype as a string and pull the first 3 characters of the string parameter.
Doug