@Veti Thank you. That worked (confirmed by M122).
I'd assumed from the upgrade instructions (Users running RepRapFirmware 3.0 or later should be able to upgrade by uploading file Duet2and3Firmware-3.2.zip. The individual files are also included here in case of difficulty.) that everything needed would either be in the "Duet2and3Firmware-3.2.zip" or in list . The list does not include a copy of "Duet2CombinedIAP.bin" and it doesn't seem to have been retained on my DUET SD card from my previous update to RRF3.0. But, my problem solved in double quick time. Thanks again.