But you can compare your debug output below:

+ 'ssh processing-02@192.168.1.124 /home/processing-02/Documents/Scripts/d2u_and_nconvert.sh '

with the same debug output from the script I gave you.

+ ssh -f me@localhost /home/me/bin/some_work.sh

Compare the lines very carefully, and you'll notice yours is single quoted, and mine is not.
Hence, your script tries to run the entire line as if it was 1 command, mine sees multiple
words (ssh, -f, me@localhost, /home/me/bin/some_work.sh).

You said the only thing you changed in your script was changing the use of array variables.
If it worked before, then you must have changed something else. So, ask yourself, why
does your line above look like 1 very long word and mine 4 words? What causes
words to be separated in the shell? You added it to your script, so you must have an idea
of what I'm talking about...