Let me know also if you find a way that makes it happen once in a while.
Upload worked for some folders, but others could not be uploaded to,
and I hadn't made any changes to upload permissions, just went to 272.
I wasn't sure if it was a hfs problem, or a system problem.
I removed the folders that didn't work from the vfs and saved, then added them again.
Since then upload seems to be OK with them. So....