I dont have your data, but I see nothing wrong with your script. eg, I did the following here
set headsep on
set term off
set newpage 0
set space 0
set colsep ;
col name format a1024
set feedback off
set termout off
set heading on
set echo off
set pagesize 0 embedded on
set trimspool on
set linesize 10240
set numw 3
set escape #
spool c:\temp\xyz.lst
select
TABLE_NAME||':'||
TABLESPACE_NAME||':'||
CLUSTER_NAME||':'||
IOT_NAME||':'||
STATUS||':'||
PCT_FREE||':'||
PCT_USED||':'||
INI_TRANS||':'||
MAX_TRANS||':'||
INITIAL_EXTENT||':'||
NEXT_EXTENT||':'||
MIN_EXTENTS||':'||
MAX_EXTENTS||':'||
PCT_INCREASE||':'||
FREELISTS||':'||
FREELIST_GROUPS||':'||
LOGGING||':'||
BACKED_UP||':'||
NUM_ROWS||':'||
BLOCKS||':'||
EMPTY_BLOCKS||':'||
AVG_SPACE||':'||
CHAIN_CNT||':'||
AVG_ROW_LEN||':'||
AVG_SPACE_FREELIST_BLOCKS||':'||
NUM_FREELIST_BLOCKS||':'||
DEGREE||':'||
INSTANCES||':'||
CACHE||':'||
TABLE_LOCK||':'||
SAMPLE_SIZE||':'||
LAST_ANALYZED||':'||
PARTITIONED||':'||
IOT_TYPE||':'||
TEMPORARY||':'||
SECONDARY||':'||
NESTED||':'||
BUFFER_POOL||':'||
FLASH_CACHE||':'||
CELL_FLASH_CACHE||':'||
ROW_MOVEMENT||':'||
GLOBAL_STATS||':'||
USER_STATS||':'||
DURATION||':'||
SKIP_CORRUPT||':'||
MONITORING||':'||
CLUSTER_OWNER||':'||
DEPENDENCIES||':'||
COMPRESSION||':'||
COMPRESS_FOR||':'||
DROPPED||':'||
READ_ONLY||':'||
SEGMENT_CREATED||':'||
RESULT_CACHE
from user_tables;
spool off
and the output was definitely more then 3 columns
TABLE_NAME||':'||TABLESPACE_NAME||':'||CLUSTER_NAME||':'||IOT_NAME||':'||STATUS||':'||PCT_FREE||':'||PCT_USED||':'||INI_TRANS||':'||MAX_TRANS||':'||INITIAL_EXTENT||':'||NEXT_EXTENT||':'||MIN_EXTENTS|
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ORDERS:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N:20:5:0:0:0:27:0:0: 1: 1: N:ENABLED:20:11-MAR-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
PARTS:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N:9991:202:0:0:0:132:0:0: 1: 1: N:ENABLED:9991:15-MAR-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
MLOG$_PARTS:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N::::::::: 1: 1: N:ENABLED:::NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:NO:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
TEST_VARRAY:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N:4:5:0:0:0:13:0:0: 1: 1: N:ENABLED:4:07-APR-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
EMP:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N:14:5:0:0:0:37:0:0: 1: 1: N:ENABLED:14:15-APR-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
FINANCIAL_RESULTS:USERS:::VALID:10::1:255::::::::YES:N:0:0:0:0:0:0:0:0: 1: 1: N:ENABLED:0:12-MAY-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:NO:DEFAULT
ACCOUNT_EXTRACT:USERS:::VALID:10::1:255::::::::YES:N:0:0:0:0:0:0:0:0: 1: 1: N:ENABLED:0:12-MAY-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:NO:DEFAULT
LOCAL_BLOB_COPY:USERS:::VALID:10::1:255:65536:1048576:1:2147483645::::YES:N:1:4:0:0:0:244:0:0: 1: 1: N:ENABLED:1:30-JUN-16:NO::N:N:NO:DEFAULT:DEFAULT:DEFAULT:DISABLED:YES:NO::DISABLED:YES::DISABLED:DISABLED::NO:NO:YES:DEFAULT
...
...
so my guess is that you've got a data issue.
Try doing a dump() around your entire string and see if anything (chr(0) etc) could be messing things up.
Hope this helps.