Last column is getting deleted

Hi,
I am having a problem in the below code:-.

$ cat x.csv
baseball,NULL,8798765,Most played,0,5,12367,NULL,NULL,98,67,Reason is not sufficient
baseball,NULL,8928192,Most played,0,4,76893,NULL,RAW,54,78,Reason is not sufficient
baseball,NULL,5678945,Most played,9,2,1,6,NULL,6789,123,Reason not conclueded
cricket,NOTNULL,125782,Usually played,NULL,NULL,NULL,NULL,123,67,Reason not conclueded
cricket,NOTNULL,678921,Usually played,NULL,NULL,NULL,NULL,563,NULL,Reason not defines


Expected output
===============
baseball,NULL,8798765,Most played,0,5,12367,NULL,NULL,98,67,Reason is not sufficient
        ,NULL,8928192,Most played,0,4,76893,NULL,RAW,54,78,Reason is not sufficient
        ,NULL,5678945,Most played,9,2,1,6,NULL,6789,123,Reason not conclueded
cricket,NOTNULL,125782,Usually played,NULL,NULL,NULL,NULL,123,67,Reason not conclueded
       ,NOTNULL,678921,Usually played,NULL,NULL,NULL,NULL,563,NULL,Reason not defines

but the output that is displayed is :-

$ nawk 'BEGIN{FS=","}!a[$1] {print;a[$1]++;next}{print FS$2FS$3FS$4FS$5FS$6FS$7FS$8FS$9FS$10FS$11FS12}' x.csv
baseball,NULL,8798765,Most played,0,5,12367,NULL,NULL,98,67,Reason is not sufficient
,NULL,8928192,Most played,0,4,76893,NULL,RAW,54,78
,NULL,5678945,Most played,9,2,1,6,NULL,6789,123
cricket,NOTNULL,125782,Usually played,NULL,NULL,NULL,NULL,123,67,Reason not conclueded
,NOTNULL,678921,Usually played,NULL,NULL,NULL,NULL,563,NULL,Reason not defines


The last column in row 2 and rown3 is getting deleted

Please somebody help me

awk 'BEGIN{FS=OFS=","}!a[$1]{print;a[$1]++;next}{$1="\t"}1' x.csv

Thanks very much.

Why was it not working in my code ?
Can you please explain the code that you have written

Thanks

---------- Post updated at 01:28 AM ---------- Previous update was at 01:18 AM ----------

The code is leaving a spacei.e a box sign, when i attach it and send it to my mail id

In fact, I don't check your code at all. I just give you my code directly.

Normally I don't write code to list all column one by one.

Ohh I resolved the issue of the space ...i replace the \t with " " and it worked...