I quickly scanned the posted code. The problem is that the layout is like this:

WHILE (condition)

BEGIN;

BEGIN TRY

-- Do something that might fail

-- Find next row to process

END TRY

BEGIN CATCH

-- Handle error

END CATCH

END; -- Ends while loop

If you get a failure, control passes to the CATCH block. So the last part of the TRY block, where the next row is read, is never reached.

Try rearranging like this:

WHILE (condition)

BEGIN;

BEGIN TRY

-- Do something that might fail

END TRY

BEGIN CATCH

-- Handle error

END CATCH

-- Find next row to process

END; -- Ends while loop