OCTET_STRING encoding issue with UPER

[nprobert]

I'm using the SAE J2735-2016 .ASN file. I'm trying to encode an RTCM message (decode works), but it's failing on the OCTET_STRING_uper.c (line 268). As you can see there's a really big number in this debug message which doesn't look right:

Encoding RTCMmessage into 17179869185 units of 8 bits (1..1023, effective 10) (OCTET_STRING_uper.c:252)
Failed to encode element RTCMmessage (OCTET_STRING_uper.c:268)
Failed to encode element RTCMmessageList (constr_SEQUENCE_OF_uper.c:82)
Failed to encode element value (OPEN_TYPE_uper.c:114)
J2735 Encoded: out=-1
Freeing RTCMmessage as OCTET STRING (/home/neal/ProbeStar/GitHub/libj2735v2016/src/OCTET_STRING.c:102)

The C code is here:

#include "MessageFrame.h"

static int msg_count = 1;

int j2735_encode(const char *raw, int size, char *buf, int max)
{
  MessageFrame_t  frame;
  memset(&frame, 0, sizeof(frame));

  RTCMcorrections_t *rtcm = &frame.value.choice.RTCMcorrections;

  A_SEQUENCE_OF(RTCMmessageList_t) list;
  memset(&list, 0, sizeof(list));

  if (!raw || !buf)
    return 0;
  
  // clip
  if (size > 1023)
    size = 1023;

  printf("J2735 Encoded: in=%d, max=%d\n", size, max);

  // build message
  RTCMmessage_t *oct = OCTET_STRING_new_fromBuf(&asn_DEF_RTCMmessage, raw, size);
  ASN_SEQUENCE_ADD(&list, oct);

  // build correction
  rtcm->msgCnt = msg_count++;
  if (msg_count>=128)
    msg_count = 1;
  rtcm->rev = RTCM_Revision_rtcmRev2;
  rtcm->timeStamp = NULL;
  rtcm->anchorPoint = NULL;
  rtcm->rtcmHeader = NULL;
  rtcm->regional = NULL;
  ASN_SEQUENCE_ADD(&rtcm->msgs, &list);

  // build frame
  frame.messageId = 28;   // RTCM
  frame.value.present = MessageFrame__value_PR_RTCMcorrections;

  // encode
  asn_enc_rval_t rc;
  rc = uper_encode_to_buffer(&asn_DEF_MessageFrame, NULL, &frame, buf, max);

  printf("J2735 Encoded: out=%ld\n", rc.encoded);

  free(oct);

  // check
  if (rc.encoded == -1)
    return -1;

  return rc.encoded;
}