Blu Age L3 - Issue with SORT utility

Job - COMBTRAN, Step - STEP05R, Program - SORT

The issue appears to be with the SORT utility. The first step in this job is supposed to read all the records from two GDGs, sort them, and write into a new GDG. In my case instead of reading all records, it is reading just one record from each input GDG. So I end up getting only 2 records in the output GDG.

The first input GDG has 262 records.

The second input GDG has 50 records.

The output GDG should get generated with 312 records, instead it has only 2 records. It appears as if the SORT program encounters end-of-file just after 1st record.

Investigation:

1. I verified that the COMBTRAN.groovy script matches with the sample provided here -https://static.us-east-1.prod.workshops.aws/public/170db278-278e-4aeb-b1cf-a6597ff7c6ef/assets/scripts.zip. This means the changes that were done as part of the workshop are all correct.
2. I created a new groovy script to just test whether the SORT is working on a different file or not and I kept only 1 input file. This time also the output file got generated with just 1 record. This only proves that the SORT is finding end-of-file somehow at the end of first record. Input file - Output file -

Can you please help to identify what might be causing this?

Thank you!