>> I think the problem is that we are having a hard time imagining just what those issues might be.
Maybe they used it like:
// write stuff
BackupWrite(some async handle);
// wait for write to finish
WaitForMAGIC();
And MAGIC is something that only happened due to the erroneous use of BackupWrite.
Am I the only one uncomfortable with the fact that the backup software I might trust my data with is written so poorly that it depends on obscure bugs?