Why would a Publish transaction change from "Transport service unable to transport" to "Success"?
tridion
Solution
I'd assume that once a publish transaction reaches an error state it will be "beyond repair". But clearly that is not happening in your case. The fact that you reload the transactions in the Publish Queue window has no effect on what the publisher does, so it is most likely that the publisher and transport service are still working on the transaction.
My advice would be to switch the log level of the transport service to DEBUG and see if anything related to these transactions shows up in there.
Problem
Sometimes when mass publishing there will temporarily be failed items with the error Transport service unable to transport Refreshing the Publish Queue a few times will then result in a success being returned. Why does this happen?