When checking to see if there was already a bug for this, I found #4462, which seems very similar. The problem is, it is marked as resolved as of r33091, and I am running the alpha, which reports itself as r33109.
The issues are the same. While the bug was fixed in r33091 trunk the fix wasn't merged into the alpha branch, because it was already frozen at that point in time. So, no need to reopen that bug. You could try a more recent nightly image, which should include the fix (see haiku-files.org ).
Regards Michael