>What's the nature of the corruption
Its unclear, file attributes, names, size all appear the same from ls output.
I initially discovered it while setting up a local repo, dpkg didn't recognize
the deb file output.
Diff throws IO errors.
Copying with cp appears to work (failing silently)
dd & r
What's the nature of the corruption? For example is there too little data?
How do you mean "flush of the write buffer"?
3 seconds sounds way too short to actually write the data.
I presume you're unmounting the device before ejecting it?
Note cp is just doing read/write so unlikely to be the issue.