Yep, it’ a weird one. Nothing in the trash.
I suspect it’s irresolvable, but anyway…
For the master exports, I just exported as sequence settings from FCP onto my external drive.
for the media managed project, I opened up media manager, selected the external drive as the destination, saved and recompressed to there.
Checked that they’d gone onto the drive in the facility – they had.
Checking back at home – they ain’t there.