Insert from remote table using unpivot - oracle11g

Question

So, there's a table for scheduling in our organization and reporting data from it. A schedule line has a column for each day of the week with values of 'Y' or 'N' depending on whether or not there is a meeting on that day. I have managed to use UNPIVOT to do this in a simple select, but, unfortunately, our needs are more complex than that.
I need to insert into a local table with a query from the schedule table on a remote table over a DB_Link, which is unpivoted, something like:
SELECT *
FROM (SELECT class_nbr,
TERM,
MON,
TUES,
WED,
THURS,
FRI,
SAT,
SUN
FROM schedule_tbl) sched
UNPIVOT (wkDay FOR DayWeek IN (MON, TUES, WED, THURS, FRI, SAT, SUN)) piv
WHERE piv.WkDay = 'Y'
Again, this works fine when I run it in Sql Developer against the server where the schedule_tbl lives. I get results like
Class_nbr TERM DayWeek
1234 Fall MON
1234 Fall Wed
....
However, amazingly, when I try to insert the result of this from a different server like
INSERT INTO other_table (class_nbr, TERM, DayWeek)
SELECT *
FROM (SELECT class_nbr,
TERM,
MON,
TUES,
WED,
THURS,
FRI,
SAT,
SUN
FROM schedule_tbl#db_link) sched
UNPIVOT (wkDay FOR DayWeek IN (MON, TUES, WED, THURS, FRI, SAT, SUN)) piv
WHERE piv.WkDay = 'Y'
what happens is that only rows with DayWeek = 'MON' are inserted. The actual number of Monday rows which should be inserted are. I'm not sure where this is breaking down. If I change the order of the UNPIVOT columns, making TUES the first one, then only the Tuesday rows are inserted (again, the correct number).
Edit: I think I can share my actual code here. Keep in mind that if I take this exact query to the remote database and remove the dblinks, I am getting more than just Monday rows:
SELECT '%processinstance',
0 ,
crse_id ,
crse_offer_nbr ,
strm ,
session_code ,
class_section ,
subject ,
institution ,
facility_id ,
' ' ,
' ' ,
'0001484' ,
'4' ,
PDB_DE0120_TRM_ID ,
subject || catalog_nbr ,
strm || class_nbr ,
to_char ( start_dt , 'YYYYMMDD' ) ,
to_char ( end_dt , 'YYYYMMDD' ) ,
DECODE(DAYWEEK,'MON', 'M', 'TUES','T', 'WED','W', 'THURS','R', 'FRI','F', 'SAT','S', 'SUN','X'),
nvl ( to_char ( meeting_time_start ,'HH24MI' ) ,'9999' ) ,
nvl ( to_char ( meeting_time_end ,'HH24MI' ) ,'9999' ) ,
' ' ,
' ' ,
' ' ,
0 ,
'S' ,
'C' ,
decode ( instruction_mode ,'HB' ,'X' ,'DL' ,'X' ,'N' ) ,
' ' ,
' ' ,
' ' ,
' ' ,
' ' ,
'E' ,
SYSDATE ,
' ' ,
SYSDATE,
' ' ,
' '
FROM (SELECT A.crse_id ,
A.crse_offer_nbr ,
A.strm ,
A.session_code ,
A.class_section ,
B.institution ,
A.facility_id ,
B.instruction_mode,
B.SUBJECT,
B.CATALOG_NBR,
A.meeting_time_start,
A.meeting_time_end,
B.START_DT,
B.END_DT,
B.CLASS_NBR,
C.PDB_DE0120_TRM_ID,
MON,
TUES,
WED,
THURS,
FRI,
SAT,
SUN
FROM PS_CLASS_MTG_PAT#CSDV1 A
INNER JOIN PS_CLASS_TBL#CSDV1 B
ON A.STRM = B.STRM AND
A.CRSE_ID = B.CRSE_ID AND
A.CLASS_SECTION = B.CLASS_SECTION
INNER JOIN PS_FSC_SRPT_TRM_VW#CSDV1 C
ON C.STRM = B.STRM AND
C.ACAD_CAREER = 'CRED'
WHERE A.STRM = '2182' AND
(B.CLASS_STAT <> 'X' OR
(B.ENRL_TOT > 0 AND
B.ENRL_STAT <> 'C')) AND
B.acad_group NOT IN ( '11','12','13','23','80','99' )) B
UNPIVOT EXCLUDE NULLS (wkDay FOR DayWeek IN ( MON AS 'MON', TUES AS 'TUES', WED AS 'WED', THURS AS 'THURS', FRI AS 'FRI', SAT AS 'SAT', SUN AS 'SUN')) piv
WHERE piv.wkDay = 'Y';
Second update: As requested, I am pasting the corrected query:
SELECT '%processinstance',
0 ,
crse_id ,
crse_offer_nbr ,
strm ,
session_code ,
class_section ,
subject ,
institution ,
facility_id ,
' ' ,
' ' ,
'0001484' ,
'4' ,
PDB_DE0120_TRM_ID ,
subject || catalog_nbr ,
strm || class_nbr ,
to_char ( start_dt , 'YYYYMMDD' ) ,
to_char ( end_dt , 'YYYYMMDD' ) ,
DECODE(DAYWEEK,'MON', 'M', 'TUES','T', 'WED','W', 'THURS','R', 'FRI','F', 'SAT','S', 'SUN','X'),
nvl ( to_char ( meeting_time_start ,'HH24MI' ) ,'9999' ) ,
nvl ( to_char ( meeting_time_end ,'HH24MI' ) ,'9999' ) ,
' ' ,
' ' ,
' ' ,
0 ,
'S' ,
'C' ,
decode ( instruction_mode ,'HB' ,'X' ,'DL' ,'X' ,'N' ) ,
' ' ,
' ' ,
' ' ,
' ' ,
' ' ,
'E' ,
' ' ,
' ' ,
' '
FROM (SELECT A.crse_id ,
A.crse_offer_nbr ,
A.strm ,
A.session_code ,
A.class_section ,
B.institution ,
A.facility_id ,
B.instruction_mode,
B.SUBJECT,
B.CATALOG_NBR,
A.meeting_time_start,
A.meeting_time_end,
B.START_DT,
B.END_DT,
B.CLASS_NBR,
C.PDB_DE0120_TRM_ID,
MON,
TUES,
WED,
THURS,
FRI,
SAT,
SUN
FROM PS_CLASS_MTG_PAT#CSDV1 A
INNER JOIN PS_CLASS_TBL#CSDV1 B
ON A.STRM = B.STRM AND
A.CRSE_ID = B.CRSE_ID AND
A.CLASS_SECTION = B.CLASS_SECTION
INNER JOIN PS_FSC_SRPT_TRM_VW#CSDV1 C
ON C.STRM = B.STRM AND
C.ACAD_CAREER = 'CRED'
WHERE A.STRM = '2182' AND
(B.CLASS_STAT <> 'X' OR
(B.ENRL_TOT > 0 AND
B.ENRL_STAT <> 'C')) AND
B.acad_group NOT IN ( '11','12','13','23','80','99' )) B
UNPIVOT EXCLUDE NULLS (wkDay FOR DayWeek IN ( MON AS 'MON', TUES AS 'TUES', WED AS 'WED', THURS AS 'THURS', FRI AS 'FRI', SAT AS 'SAT', SUN AS 'SUN')) piv
WHERE piv.wkDay = 'Y';

Answer 1

This isn't a completely satisfactory solution, but it is working for me. If I remove two expressions from my select clause (any two columns), this issue disappears. This is obviously a previously unknown Oracle issue involving DB Links, as if I take the same query and run it on the remote server where the tables live it is not present, and there is nothing in the Oracle documentation regarding DB Links about this. I will at some point attempt to raise it with them.