Originally Posted by robj
It is easily reproducable and looks like its been there for quite some time, the current 0.196 has it, and looks like back to 0.158, but 0.153 is ok.
I don't think this is specific to the Apple or any particular format as I've also had BBC users reporting to me something similar. I have been able to replicate the issue myself with bbcb and a ssd format floppy and it seems to insert an extra byte after the first sector rendering the image corrupt. Haven't yet investigated further as it seems core floppy image related.

BBC Model B, ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, etc.