You need to have
Code:
writable_floppy_images = 1
in your config to be able to write to the images. Otherwise it's saved for session only.
IMO better way for transferring files between the A1200 and PC is to get the pcmcia card reader for CF carts, and use fat95[1] and compactflash.device[2].
[1]
https://aminet.net/package/disk/misc/fat95
[2]
https://aminet.net/package/driver/media/cfd