It probably only happens with very big files. I suppose it happens when the file size multiplied by the width of the status window results in a number which is bigger than 2GB or bigger than 4GB. Then an overflow occurs and the result is either negative or very small which causes the progress bar to disappear.
I assume there are not many people who use Workbench to copy files at all and if they do, they probably don't disable AsyncWB.
Bye,
Thomas
