I have a PCS484GGUS Thermador Professional cooktop. Front left burner has had problems for a long time with staying lit. Burner would frequently go out, igniter would start clicking. Now, it doesn’t come on at all and the igniter doesn’t make a sound. I don’t understand how the system works, so don’t know what to look for. All the other burners work fine and have never had a problem.
The PCS is the cooktop-only version of the PRDS, i.e. the cooktops are the same.
Edit: With your issue, you may also want to measure the resistance of the solenoid, which should be 1760 ohms. The burner dropping out mid-cycle is more indicative of a solenoid over heating and opening up, stopping gas flow. It continues to spark because the spark module is still looking for a flame and tries to re-ignite the burner.
KC