I replaced the spark module as well as the wiring harness. I think it was the spark module that was the main culprit, but decided to order and replace both items because I did not want to find out it was the other one and have to wait 2 more days for the part.
Now all 5 burners spark reliably, and seemingly faster. It was a slower tick-tick-tick sound prior to replacing the spark module. After installing the new module, the spark is brighter and faster. The spark module is physically different, so they must have upgraded the working circuitry compared to the OEM part.