Thanks Pierre, I've been pulling my hair out. I've downloaded 5.3.8 from WA and the batch process works. Appreciate your help!

Thanks for responding. Do you know where I can obtain a copy of K version 5.3? As this is for basic voluntary bat work, I can't afford a pro licence and don't need that level of functionality.

Thanks for responding. Can you tell me why this is the case? Also, do you know where I can obtain a copy of K version 5.3?

Of course, thanks Alex. That's what it must have been. There is a fair bit of corrosion and still some residue in/around the microSD slot (and on the card itself) but the device is still recording WAV files (and the waterproof case is still solid).