Export silently fails

Trying to do a *.1pux export from the desktop app on linux (1Password for Linux 8.12.5 81205001), it silently fails. The password is definitely correct (if not, I get a 'That didn't work ..' message). But when I hit the 'Export Data' button, it spins for a moment then .. nothing. I assume the next step should be a dialogue to choose the file name & location, but the button just re-enables after a brief spin. Same if I choose csv export.

I've done a comprehensive search for 1pux files on my drive, just in case one was dumped somewhere unexpected, but no.